EDP: Muting input in Multiply

[Sam Rogers <onemouthband@yahoo.com>]

Here's what I want to do using footcontrollers, and I guess
I just need to hear from someone that it's possible or not
before invest in more equipment or give up on trying. If
I'm missing something obvious that will achieve the same
result that's great news too!   
- record a drum loop (say 2-bars)
- end by entering NextLoop (LoopCopy=On), lay in a bassline
of equal length
- end by entering NextLoop, the third and final loop
- mute input (via footpedal switch TBD) while singing
lyrics, unmuting for specific sections to add to this
longer loop (16-bars)
- end by re-entering first (drum) loop in Multiply mode,
add new bassline/guitar/vocals for chorus
- alternate between loops 3 and 1 in Overdub mode, again
muting and unmuting the input signal to add next notes of
chord at each pass, without letting lyrics enter the loop
- vamp out on loop 2 applying same mute/unmute approach to
2-bar phrase, gradually reducing feedback to zero.

I have been through the archives a lot lately, but haven't
hit upon anything that addressed my specific question. I'm
sure dozens of you must have tried something like this
before. Anybody pull it off?  If so, what are you using as
a momentary switch to mute your input? I understand MIDI
controllers can't be used to change input levels on the
EDP.
Thanks!

Sam Rogers
OneMouthBand
www.OneMouthBand.com