CELLULAR SOLUTION: Those yellow call boxes lining Ventura County highways are a godsend if your car becomes disabled. But what if you're disabled, too? The county Transportation Commission's solution--cellular phones--will be distributed by summer's end to 100 disabled residents. . . . "They only go to 911," said Gerald Dominick, who serves on a planning committee. "Some people think this is a good way to get a cellular phone. It isn't." So which of the county's 457 call boxes gets the most use? Street Smart knows (B1).