I don't have the drawing, but if you do a search you should be able to find one. Pretty simple just need some radio shack parts and be able to splice them in to your O2's. Off hand I think you need two 1 meg ohm resistors(1/2 or 1/4 watt) and two 1 micro farad capacitors.
I made my own and it cost me like $3 and took long enough to cut and splice the resistors and capacitors in. I thought that it was a very worthwhile mod so I posted a scematic. On a scale of 1-10 in difficulty I would give it a 3 only because you have to be able to read.