^---Did that on a stock verizon rom the mr2 rom I believe it is. Doesn't require a data plan as I don't have one and it is blocked on my phone.
I don't believe this uses agps just unlocks the regular gps. Sometimes takes a little to lock but once it does it works great.
When I was stuck trying to unlock it the main thing i forgot to do was use qpst---service programming----gpsone tab. Should work with no problem. I don't know about this on custom roms though....
Also if your trying to use the internal gps programs like google maps won't work because they require a data plan or at least internet service of some sort like wifi which obviously sucks. I'm sure you already knew this just thought I'd point it out..
Where can one get Garmin XT?