there is no aux input...get an aftermarket HU (headunit)! If you have a GTP there may be a cord already run but i think you would see it if there was one there...
if you want to diy though for future reference, you pop off the ignition bezel first with a flat object (i used a flathead screwdriver with some electrical tape over it to prevent scratches).
then start at the lower left hand corner of the trim and start pulling it off. it seems pretty flimsy and feels like it will break, but if you are careful it will come off...
from there you must start at the bottom and remove the storage din, then the hvac control, then finally the stereo with the appropriate socket...
voila...
