What is the best way to get off easy in a drug related case?

My boyfriend was recently charged with a ps of cs1<4 grams. He was on parole and now he has caught this case and he might go back to prision for the rest of his four years. He has signed an admissions guilt like a dummy so theres really not alot of leadway for him. Also someone else was in the car with him and was thinking about taking the case for him could that help him? And I was wondering could he play like he is an addict and just possibly just get probation on this case and just get sent to a rehab or something. He talkedto his parole ppl and they said depending on how the case goes depends on if theyll revoke him. What is the likelihood of him convincing him he has a drug problem and also what do you think would be some other options???