I never took one. I went from BOTC to SLT and right into MOC training.
CAP is for the purple trades that can be posted to an army unit, I think CELE officers take it as well as security officers (MP's) and a few other trades. Hard Air Force trades like AERE, Navs, and Pilots don't take CAP. The TacHel types will do LOFT which is a basic intro to the army and how they operate. MH types will do a condensed version of NETP which is damage control, fire fighting and "the pointy end is called the bow" basic naval knowledge.
There is a course called the Air Force Officer Basic Course (AFOBC) that is usually completed a couple years after being MOC qualified. I have no idea what's taught since I haven't done it yet.