So I have a homebuild amp (tubes ) with 2 tubes. My preamp has 2 stages and then one more stage + cathode follower.
I have a 2nd gain pot, that when at "0" it has a switch and bypasses the 3rd+cathode follower (so it only has two stage before the tone stack), when I remove it from 0 the sound goes to this 3rd stage.

What I want to do is make an option for footswtich in which:
1.When the gain pot is at 0(bypass) it will not do a thing
2. When the gain pot is >0 (sound goes to 3rd stage) I can switch between 2 stages and the 3 stages.

What's the best way to do this?
I have a footswitch button that only has two lugs(do I need a 4 lugs?). And if so, can I do this with a mono cable, for a dpst I need a stereo right?
I guess I have to put the footswitch before the pot (btw the pot function to change resistance is independent from the switching capabilty) and when the cable is connected the switching from the pot is completely bypassed(thing is I can't do function number 1 that I explained before).

Thanks for any ideas. And I'm pretty sure I complicated the text..