There seems to have been a bit of confusion regarding exactly what Chax as an application means. All the Chax application does is serve as a gateway into iChat. It isn't a tricky reimplementation of iChat or anything wild, it just allows Chax to insert itself into iChat at launch time.
Since Chax now uses Sparkle, you should be able to upgrade from alpha 1 directly from iChat.
Changes from Chax 3.0 Alpha 1:
- Added auto-accept options
- Added activity window
- Added DisableFocusRing hidden default
- Fixed the unified contact list not remembering its position across launches
- Fixed contacts from appearing stacked up on each other in the contact lists