BTSync 2.0 just came out, and I think is reasonably accessible. However, in 1.4 you can skip creating a username and password and bypass creating a Sync account, but now it appears you cannot.
The issue here is that VoiceOver does not focus in the edit fields correctly, and the action that I'd think to take, which is pointing the mouse at and clicking, does not seem to work.
Any suggestions? After that I don't think I'll have any problems.