Yes you should be able to. The Palm V has a nice clip-on GPS unit from Delorme (I think), however, I suspect this won't fit the new series, given Palm's propensity for making external case mods with each device. So you will probably be stuck with a serial interface connection to a GPS unit.
Software - take a look both at
www.pilotgear.com as well as
www.gpspilot.com
Let us know how you get on. I'm interested myself but haven't quite figured out whether to go the Palm or PocketPC route.
David.