Well let's see if I can recall the settings. I just played at lunch, so it's not like it's been an eternity or anything
Level - 5 o'clock...all the way up. This is the equivalent of a makeup gain setting on a normal compressor. I like the boost it gives me since I usually only use it for soloing.
Tone - about 1 or 2 o'clock...just enough to roll off the harshness in the high-end.
Attack - about 9 o'clock. I like a slow attack because I really love that Mick Ronson kind of "tube amp about to explode" sagging rectifier kind of sound.
Sustain - between 3 and 5 o'clock...basically all the way up. Normally, I want to be able to hit a note and let it ring for an hour if need be. At this high of a setting, the input signal would have to get pretty darn quiet to fall below the compression threshold. It is very pumpy at this high of a setting, though. Try between 1 and 3 o'clock for less pump, but less sustain.
I really want to try out some other compressor pedals, especially things like that BlackFace or BlackFinger or whatever. It's like an optical tube compressor in a pedal, and looks pretty enticing. Also I saw one in Musician's Hotline or whatever that advert/mag is for high-end gear. It looked just like a MXR pedal, same knobs and style at least, but it was silver and had 2 knobs and a switch.
I've come to terms with the fact that the CS-3 isn't a great compressor, but for $70 I cant see any others that would come close to it in performance and reliability. I've had mine for 4 or 5 years now and it still gets stomped on a lot every time I play!