yes it can be done, search for uclinux (its 68k based) but outta all the palms the UX series would be the best platform for linux port (since it has system/heap ram, user ram, etc..)
Only problem is it's made by sony so your SOL cause they will not provide any developer details on the core hardware, so you'll need to bust your UX50 in half with a hammer solder up some jtag lines/debug serial/etc... and start trying to figure out all hardware calls/address/etc..
goodluck