It is a torx not allen. I don't have the size but I know it is a torx for my envoy.
OP: you can get around having to take the center console out to get the plastic trim panel off around the hvac and stereo. What I do is unscrew the 4 phillips screws that hold the carpeted enclosure in the center of the truck underneath the part of the dash that contains the hvac and radio. Then I spread that plastic cover open on both sides and slide it down the hump until I can see the 2 phillips screws that hold the bottom piece of the beauty panel on for the radio. Use a magnetic screw driver to help you prevent from dropping it down the cavity. I then tilted the top vents up all the way so I can put my thumb in there and grab the top and pull it straight out and then I can pull it out far enough to get the retaining clips free and then pull straight up to get it out of the bottom. as a note you might want to engage your parking brake and shift the trucks transmission into 1 so that when you tilt that beauty panel forward it doesn't strike the shift knob and make it harder to remove.
I never once pulled my center console out when I was playing with the hvac and radio and I have taken it apart probably 10 times now because I always find a need to get back in there. To be honest these are not very fragile. I ripped mine out in 20 degree weather a few times and though my hands were freezing and couldn't feel anything I still pulled it out and didn't snap a single thing.
