thats not his problem. Verizon has some kind of lock so that only verizon navigator works on the mr1 rom. There is some hack you have to do to let 3rd party apps access the gps. Even if you flash to a custom rom after the official verizon 6.1 update.
Try following this tutorial over @ XDA as it seems to be what you need.
http://wiki.xda-developers.com/index...VerizonAGPSFix