Dammit man, where were you like 2 weeks ago when I faced this problem.

I ended up drilling out my steel frame with a 5/16 bit. It hurt to do as I didn't lube the bit, and it bit into the steel pretty nastily.

Anyway, it ended up working, but now the reach really isn't as long as advertised and doesn't seem to be doing the best job in the world. I'll post pics.

FWIW, I have Tektro R538 Long Reach (or so they told me).

Edited to add: that's my thread mentioned above.