howdy too, this is my first post since about 2 years
, but since you're question is really2 interesting, i can't help myself but to post this,
. at first many people already tried opening up their ROKR actually, and most of it found out that the internal parts are soldered or was one with it mainboard, think of it like netbook/nettop processor, if you manage to unsoldered them, and find a processor yourself i think you can physically mod it, but of course it means you know which part connect which point, since it's not like a socket base processor that can be easily identified, the modding can be really pain in head.
Oh and don't forget that to find an upgraded processor is also a pain in head, since ROKR processor is a costume-made i think not some generic interchangeable processor that PC or newer android phone have.
PS : I think i don't have to mention this, but, changing the other parts end up in the same explanation i told before.