you can do it. They will tape off the teeth so they don't get any powder on them. The high temp tape will be baked w/ the powder and when they peel it off and the finish should only affect the area's not taped.

The recessed areas where the c-ring bolts will be more problematic since you want a good mate between the bolt and the c-ring. If they tape well, or do a good job using some high-temp silicon to "mask" the recessed area, it should come out OK.

The area where the taped section meets the non-taped section may not be perfect. I have no direct experience w/ c-rings but having talked w/ powder coaters for quite a few projects I hope this provided some insight.