When a guitar is an accessory

In the new movie “Prey for Rock & Roll,” actress Gina Gershon plays the leader of a veteran all-female band slogging through the treacherous muck of L.A.’s music world. But during her House of Blues performance Thursday to promote the film and a soundtrack album, she was backed by an all-male group featuring members of the photogenic indie-rock band Girls Against Boys.

So much for life imitating art.

Maybe it was easier to get a bunch of guys to play behind Gershon, who looked the part with her cut-up T-shirt, tight faded jeans, buff arms, wild hair and smoky eye makeup -- all smartly accessorized with guitar, tambourine and jew’s harp.

But her passable vocals, modeled after such singers as Patti Smith and Chrissie Hynde, were largely unconvincing. Her enthusiasm was genuine, and her sneer-into-the-mike, swing-that-guitar! rock-star poses were note-perfect, but she never displayed the hard-living commitment of a Cheri Lovedog, the real-life rocker who wrote the stage play on which the film is based.

Part of the hourlong set offered tunes from the movie, mostly written by Lovedog, leader of the like-named ‘80s-early ‘90s L.A. group. And the scene was way more Hollywood than rock ‘n’ roll. The house was packed, yet few seemed to actually be listening, as loud chatter nearly drowned Gershon out during more subdued numbers. Although there is rage in such “Prey” tunes as the sexual-assault backlash “Every Six Minutes,” Gershon and the band rarely made the power-pop, punk and bluesy-rock more than moderately forceful. Still, she was unpretentious, and a weird selection of cover songs provided some interesting moments.

Gershon relished a punky take on Love’s ‘60s hit “Little Red Book,” and a hypnotic, somnambulant rendition of Black Sabbath’s “Paranoid” was at least offbeat. But with such encores as the Stooges’ “I Wanna Be Your Dog” and the Nancy Sinatra hit “These Boots Are Made for Walkin’,” the cliche meter spiked into the red and stuck there.