I managed to successfully install OSX 10.7.2 on my Motion LE1700, complete with tablet support, thanks to this fine person that made Tabletmagic. I do have a backup, but now that I've upgraded to 10.7.4 (via combo update), I can't make the tablet work again.
I've tried removing Apple16x50Serial.kext, rebooting, and putting it back with Kext Helper (and I checked inside it to make sure it referenced WACF004.) It does detect serial0, and Tabletmagic says it's a Tablet PC. Console output gets the geometry, if that's any help. I don't know anything else to tell you that would be useful. Does anyone have any suggestions?