snyperx:

You can also drill the mount slightly undersize for the screw, then cut some slots in the end of a screw and drive it through; that will cut the threads for you.

The proper way, as has been pointed out, is to buy a tap and tap handle, or a complete tap and die set.

Bill.

PS: You could also visit the shop where you get your car services, someone there should have the set. wr.