I exchanged my Verizon XV6900 due to a cracked housing, so I had to unlock / upgrade my phone again to get gps enabled. Since there continues to be questions on exactly how to do this, I wrote a step-by-step walk through with pictures (based on Darkflame808's "safer alternative" thread) as I did this. Hope this is helpful for those doing it for the first time.
http://www.atwistedweb.com/xv6900/index.html