You were able to change a wifi galaxy tab into a 3G tablet? Hmm. I never heard of that. I dont think there is a way to do that with the TouchPad. I believe it was made for wifi only so it doesn't have the parts inside to enable it to be 3G/4G. I think there were some 3G models made but they are rare since they were never released officially.
EDIT: I think I'm reading this wrong. lol
Galaxy Nexus / HP TouchPad (Both on Jelly Bean)
Palm Pre Plus
Everything before that doesn't matter.