I've tested the few cab files and the registry edits that worked on the TP and they activate the the "automatic b" "automatic" and "sprint" options but changing to any the options do not move me to another network's tower. Eeven though I'm getting 0 to 1 bar from the sprint tower, it stays. My old treo 700p (vzw) gets 5bars so I know there is a verizon tower close by. I'm not one of those people who will really ever use this except in extreme circumstances when traveling. I switched with the expectation the option was there.
I assume the roaming hack doesn't work for the TP2. The option to "find network" for CDMA stays grayed out so it can't be selected.