You can definitely do it, I am running a Sprint TP on Verizon with full data & mms, using NRG rom, latest sprint radio.
You'll need to install a DMU key (search for Vzw_Public_Dmu_10.key.zip), and program the correct vzw MIP settings thru EPST or QPST - if you don't know what these are, do a search on this site and you'll find everything you need to know about them.
See steps 5, 6, & 7 of
THIS POST for what you'll need to do regarding DMU & MIP. Follow the steps very closely.
Like I said, a careful search of this site will get you all the answers you need to get this going. Though it may take a while to figure out, it's well worth it!
Oh, and if anything I wrote here helps, I'd appreciate if you hit the 'thanks' button below.