‘90210’? Yes. ‘Seinfeld’? Not a Chance.

In the beginning, God created Elvis.

But these days, things aren’t so simple.

“There is an overwhelming sense of separation, isolation: segregation,” the great Greil Marcus wrote a few years back of his lifelong subject, popular music. The same could be said of the whole of youth culture as well.

From acid jazz to the Zulu Nation break dancers, kids’ customs have exploded into cliques more distinct, fragmented and isolated than the former Soviet Union. It is a tall task, to say the least, to provide a tasting, let alone to publish the bible of it all.

Yet two young journalists are giving it a go. “alt.culture: An A-to-Z Guide to the ‘90s--Underground, Online and Over-the-Counter” (HarperPerennial) is an earnest, compact and common-sense look at modern youth terrain, what the authors like to call a more youthful counterpart to E.D. Hirsch Jr.’s what-you-should-know handbook, “Cultural Literacy” (Houghton Mifflin, 1987).

“alt.culture” is a literary coming out for a new generation of alternative culture, which is often misinterpreted in the mainstream media. It is decidedly techno-centric, with ample coverage of electronic music, cyberculture and designer drugs. Through 900 short entries, the authors paint a picture of people raised more on computers and synthesizers than on television and guitars.

“We didn’t really enjoy the way pop culture was being portrayed,” said co-author Steven Daly, a 35-year-old magazine journalist from Britain, as he handled chopsticks at Sushi on Sunset recently.

“If you go to a bookstore, there’s a bunch of good record guides . . . sort of still centered in rock culture and the ‘60s,” said the book’s other writer, Nathaniel Wice, 27, a former editor at Spin magazine. “Rock culture is not as central to youth culture as it was a generation ago. . . . This is the idea of doing a culture guide that isn’t just about rock.

“The fragmentation of pop culture is really central to the book,” Wice said.

Right down to the title, which the authors most magnanimously defended from the publisher’s push to call the book “The A-to-Z Guide. . . .” Even these culture connoisseurs know they are not writing the last word in postmodern pop.

The press on this publication so far has been positive. But only in this brave new world would you find someone so glowingly written up in a book criticize that very book. Consider author R.U. Sirius, a head on the Mt. Rushmore of cyberculture and a subject in “alt.culture.”

“These kinds of books play well to the postmodern attention span and the desire to be hip, but they don’t really make you think,” said Sirius, who himself co-wrote a guide on cyberculture (“Mondo 2000: A User’s Guide to the New Edge,” HarperPerennial, 1992). “I would probably do another one if they paid me to do it,” he added cynically.

Likewise, Todd Boyd, a pop culture expert based at USC, said, “These kinds of encyclopedias . . . tend to be more topical and trendy than substantive.”

The authors say they put a lot of deep thought and two years of research into the tome, holing themselves up with nothing but a modem and tons of magazines to maintain sanity.

The duo, who met while working at Spin magazine, started the book by brainstorming broad categories such as comics, diseases, drugs, the Internet, magazines, movies, music, technology and television (“We did ‘90210,’ ” Wice said, “but we didn’t do ‘Seinfeld.’ ”)

They worked their way down to more minute entries, such as a two paragraph take on Ikea (“one step up from milk crates and cinder blocks”). There are also entries on subjects from “Baywatch” (“David Hasselhoff . . . presides over a group of male and female Malibu lifeguards of formidable pulchritude and questionable acting ability”) to Urban Outfitters (“subculture retailer supreme”).

Their research took them online, to the newsstand and to research services like Lexis-Nexis, which keeps a backlog of everything written in major daily newspapers.

The two admit that they don’t always swim in this brazen and varied sea of youth (you won’t find them heli-boarding down Kilimanjaro any time soon). They are, they say, stereotypically bookish scribes (Daly dresses frumpy; Wice wears school-boy specs) with an unusual appetite for all things pop.

“There were a lot of areas in the book that were out of our range,” Daly said, “from gay culture to drug culture. And there were freelancers giving us that work.” (Such as Times contributor Mark Ehrman, who penned a piece on heroin for the book. There are other essays on comics, dance hall reggae and the Internet).

In the process, the two learned more pop minutiae than they ever wanted to know:

* “It’s fun to see that Alicia Silverstone was born in 1977 and that Anka Radakovich [Details’ down-and-dirty sex columnist] was born in 1957,” Wice said.

* “One of the main engines of American pop culture is the spending power of white suburban teenage boys,” Daly said.

* With broadcasting, and now the Internet, the cliques of pop culture “are no longer geographically based,” said Wice--i.e. you can be a riot grrrl, rave-head or rapper in Reno.

* The two believe youth culture will continue to splinter. “People are so sick of the media scooping up their culture that they may get into things even more esoteric,” Daly said. “Stuff that can’t be explained in a headline.”

* The spreading tentacles of mass media will only accelerate the appropriation of urban culture (such as high fashion’s use of such street tenets as backpacks, Adidas and ski hats), Daly said. “That’s what you’re prone to when subcultures are broadcast--a cheap holiday on somebody else’s misery,” Daly said, paraphrasing a Sex Pistols’ line.

Yet here they are, exposing it all. “Our book,” Daly admitted, “is a mainstream product.”

The authors wisely retained electronic publishing rights when they signed their contract with HarperPerennial nearly two years ago (a deal unheard of today). The duo has since posted the book on the Internet for free (www.altculture.com), for “promotional” purposes. “We’re writing about this stuff,” Wice said. “We might as well participate in it.”

So far, the two say they’ve had enough “hits” (online responses) to provide as much promotional power as their press tour is generating.

But when higher-ups at HarperPerennial recently found out about the Web site, they reportedly hit the roof. And Daly and Wice suddenly found themselves the subjects of stories on the battle over online publishing rights. Publishers in general are concerned that books online are easier to pirate and that there’s no clear way yet to make money from them. “Until those issues are cleared up,” one industry expert said, “publishers will continue to restrict their use of the online world to teasers to promote books.”

It’s the kind of issue Daly and Wice sought to document in “alt.culture” (which took its “alt-dot” title from the Internet chat groups with titles such as “alt.drugs” and “alt.music”). But, in their pioneering drive to post the book on the Internet, they became a part of the story.

Everybody gets their 15 minutes, especially in this book. “That’s a big theme of the book, how alternative has become mainstream,” Wice said.

Indeed. While the kind of monolithic mass culture that Elvis inaugurated is history, the pop pie--however thinly sliced--is served up hotter than ever . . . at a bookstore near you.