There still is an archived version of the recipe site. I don't know why others are reluctant to post it but here is a link to the section that pertains to adding a PID controller to the smoke generator. The links may eventually go dead some year but they are still alive and well right now. There might be a few pics missing in that link but if you need them I can post where to d/l the entire recipe file, which includes every pic of every mod that was on the Susan Minor site.PID Controller
I followed that how-to and added one to my OBS about 5 years ago.
Edit: OK, here's the link to d/l the entire Susan Minor recipe file. It will have the rest of the pics in that how-to for installing a PID controller in the SG. You'll need the Recipe_v5 file and the GSReader v2.8, which you can find in that thread.Recipe File