Elvis Costello may not look the part, but he can rock 'n' roll. The British new wave artist will perform in concert Thursday night at 8 p.m. at the Syracuse Area Landmark Theatre (formerly Loews), on South Salina St. Also on the bill will be Mink DeVille and Nick Lowe. Costello has released two LPs on Columbia including My Aim is True and This Year's Model. His songs range from a touching ballad, "Alison" to the scathingly satiric "Watching The Detectives." For ticket information, call 375-7979.