Simple.
(#1-) Pwnage CFW 2.1. Don't even bother loading stock FW in itunes first. I feel like that puts things in the phone that screws everybody up later. CFW only in the phone seems to work smoother. (JMO) Leave installer off, just Cydia.
(2-) xs _ _ _ _ repo for 2.1 app sync (patch II). The patch was originally designed to make cracked apps work, but ironically help actual regular old paid apps work since some are buggy and have permissions issues being verified. The patch opens the gates up a bit so any apps load properly. For once hacker-ware benefits the straight and legal.
(3-) Get'r done
As I've said before too, I don't really use customize for anything, and try not to use it at all in most cases. I manually modify the springboard so it doesn't have to depend on anything else. I just replaced the dock manually on my 2.1 with no programs to depend on, no winterboard, no customize....... good old hand coding. It never fails you or conflicts.

The wallpaper is a bit more tricky. That's worth using winterboard on, really.
Here's my 2.1 phone after a few hours of work tonight.
