slashack,
I have a Dell D630, which I believe has an ALPS trackpad. When I use either your kext or the "stock" voodoo trackpad kext, the mouse tab disappears from the keyboard & mouse pref pane, there is NO trackpad pref pane, and the VoodooPS2 pref pane, when clicked, gives me an "ApplePS2SynapticsTouchPad not found error".
Looking in the console and searching for PS2, there are a bunch of ApplePS2ALPSGlidePoint: Dictionary Object: some value. Just before that is ApplePS2Trackpad: ALPS GlidePoint v8.99. Just before that is VoodooPS2SynapticsTouchPad loaded. And before that is ApplePS2Controller: Timed out on mouse input stream.
Does this help at all? The trackpad is working, but only has a hyper-sensitive, zero-modification mouse. Perhaps there is a conflict?