Check out the thread below. PalmOne released drivers for the T5 and it seems like there's a chance they work on the Treo 650 according to ShadowMite who unlocked the DUN networking.

http://discussion.treocentral.com/sh...ad.php?t=64490

I figured it might be of interest in this area because it does require an accessory (wifi card) at a minimum to make it work.