It should be clear that "sheet-metal" type self-tapping screws are a NO-GO, and violate 250.8. Like wise on the use of "Wood Screw"! You could post a picture of that in violations forum.
If this is a newer cut-ham panel, it will have 2 sets of the holes intended for this use, 1 on each side. And the applicable listed ground bar will be listed on the door lable.
If not available, most inspectors will accept a like-in-kind installtion. Using parts "listed for the purpose", like a simular ground bar with (2) 10/32 threaded screws that come with it.
gfretwell, I don't think a #4 to the main is nessesary. You'd have to find a code for that one to not twist my arm for that. Although it does the job, and does it well, it's over-kill. Conduit, cable or sized for the feeder, OK, #6 max to feeder source.
BTW, the one of very few panels that have that extra thick or deep sleeve for ground screws is SqD. Cut-ham and murray are tin-can thin these days.