You'll need to change the Arming Check (ARMING_CHECK) param within Mission Planner to ignore GPS lock before arming the motors for flight.
Not sure what your need is as far a flying the IRIS indoors but I wanted to share this in case you havn't seen it already.
And here is Chris Anderson and Brandon Hurd speaking a bit about it at ARM TechCon http://youtu.be/EwYTgzfQ-A8?t=20m40s
Thanks for the reply. The first link , on the bottom.. That guy is from my department in Naples, Italy :) I knew that project. Thanks anyway.
The second video is cool :)
I tried using these settings for an indoor flight, but was unsuccessful at arming the motors still. I had to completely disable the "Arming Check" instead of only "SkipGPS". Any ideas why that might be?
You can use a precise (+-2cm) Indoor "GPS": http://marvelmind.com/.
Here the a couple of demos: