+1 to impact screwdriver......either that or an air hammer if you have an air compressor
you can get the impact driver at the auto parts store, i believe its less than $20. just make sure you hold it on there tight so it doest walk and beat the shit out of it. its a pain in the ass to get off. i hate those fucking screws, just leave them off when you get them off. they were put in there at the factory during assembly to hold them in place. no other cars have that shit on there, they're not needed.
good luck!