I was a member of the CG AUX for a few years back in the late 90's to about 2002. I left because I moved around a lot and couldn't devote time to it. I left around the time they were talking about doing background checks but I don't know whatever happened with that. My life is more settled now so if I decided to rejoin what type of paperwork would I have to fill out? I went to the website but didn't find much information.
You may need to contact the Director's office for your District. A similar question is addressed at the Auxiliary Knowledge Base (kb.cgaux.info), although that was in regard to someone who had been out for ten years.
What's interesting is you are the second poster this week who has not been able to find helpful information at the relevant websites, a problem that really needs to be addressed and resolved.
Incorporated in that is the App, Citizenship Verification (you must have proof of same), OFI Form 86C Special Agency Check, Standard Form 85E Authorization For Release of Information.
The flotilla will provide the fingerprint cards and should arrange for free fingerprinting. You need to bring with you an original and at least 1 copy of your proof of citizenship.
You will need to pass the New Member Exam. The flotilla should help you with this (many just give you the answers so you just fill in the bubble sheet).
Read the Authorization for Release of Info carefully. Make sure you understand what info you are authorizing them to get (just about anything about you). Many now-former Auxies objected to that document and refused to sign it and are now ex-Auxies.