Yeah, and it voids the warrenty
It was quite easy but very tedious on the T-series (A metric arse-load of tiny screws, and typical Sony dense-packing of the innards), but a lot of Palms seem to be snap-lock instead of screwed-in, espescially the less expensive ones, so opening them up may require some good shivs and a careful hand...!
Sadly I haven't seen any Z22 dissassembly websites/images that might help you
