the plastic overall is rather soft and drilling is going to be tricky. I used a dremel with dremel drill bits, its really high speed and a slower drill may be safer. The drill holes were clean but bad things could easily happen.

These drilled frame pieces did not want to fit and were truly narower than the BCP frame. It took a sugnificant amount of careful force to get things lined up and the screw started, screw in, and tightened. I used a 2.4mm drill bit and 2.5mm bolts. They threded themselves into the BCP frame quite easily and are very tight. I did not see any sugnificant bulging becouse of the slightly oversized bolts. It just fit quite well, but I really had to force the frame. both the kit piece and the BCP frame are plastic both bent just enough to get things started. I'm not ready to say everyone will be this lucky but.....

Once the front and back frame were screwed in the rest was comparably easy.