I got an extender the other day and after 48 hours, and 3 reps later, one of which knew what he was doing, I finally got it to work.
Some things I learned, the red GPS light may actually mean a network/router problem (such as in my case) and nothing to do with your GPS.
Also, once locked in, you can move the unit anywhere. Once my extender was set up, I disconnected the GPS cable, snapped the module back into the unit, and stuck the unit INSIDE my cabinet. It still works great; I get signal at all corners of my house (6000sq ft spread out on 3 floors).
Do note that my HTC Inc does not display the 4 bars, unless a call is made or received. This is a known bug and not clear if it is Verizon's or HTC's fault.
Best thing, I got the unit for $65--It sold for $199 with a $100 rebate. However, the rebate form is not available, and after calling enough reps, they applied the credit to my account, and added $35 for my "trouble." All in all, worth it.