I tried this on my PPC-6600 and it seems to work just fine. :)
"AE Button Plus for HTC's Himalaya (O2 Xda II, T-Mobile MDA II, i-mate PDA), Alpine (O2 Xda IIi and similar) and Magician (O2 Xda II mini, T-Mobile compact and i-mate JAM) extends the functionality of available hardware keys on the devices above which is appreciated especially for the HTC Magician which includes four hardware buttons only, compared with the Himalaya/Alpine six buttons."
If you're looking to expand the usage of your HTC...
[Pocket PC Thoughts]