Lawyers for Barry Bonds' personal trainer say he'd rather go back to prison for a third time than take part in the grand jury investigation of his childhood friend for tax evasion and perjury. Greg Anderson had just served a 15-day jail term for refusing to cooperate in an earlier phase of the probe. Anderson is expected to be called Thursday before a new grand jury investigating the San Francisco Giants slugger. But the trainer is expected to renew his vow of silence. "He's resigned to do whatever it takes to maintain his integrity," said Paula Canny, an attorney and close friend of Anderson.