That's a security feature; they are shear-head bolts, the heads of which shear off when fitted at the factory, leaving the assembly tamperproof but also leaving the legitimate owner with no easy means of removing them. The procedure stated in the Ford manual is to cut new slots in them using a hammer and chisel, and then remove with a screwdriver, or you might also be able to get a hacksaw blade in there and cut new slots that way. This page is from the '95 manual but I guess your 2000 will look similar. See the fourth diagram down:
http://www.freewebs.com/selectron/ig...k-cylinder.htm