Is it possible to reenlist with a Chapter 9, RE-4, Honorable?

Your best bet would be try to talk to an active Recruiter, as they'll have the most up to date idea. But good luck finding one who's going to give you the time of day with that Discharge type. I'm not even sure if that sort of RE-4 is waiver-able, since you already failed your chance to get over your substance abuse problem on the Army's dime.

I'm pretty sure a RE-4 code is NON-waiverable no matter the circumstances.

RE4 is not waiverable.

If you can find it, look for AR 601-280 The Army Retention Program.. especially chapter 2. Or, go talk to a recruiter

Check AR 601-210, that is the guide you need. I don't think it's possible.

Short answer: No.

RE CODE 4 is a permanent disqualification for the Army. So the answer is NO.