So, if I'm understanding the thread correctly, the only reason it's not true bypass is so it can blast on in momentary mode when "bypassed"?
All that function needs is an "always on" input to circuit. You can put a really quiet load free input reference to the rest of circuit that will "sniff" your signal when in bypass, with a parallel momentary to rip the thing into the chain when needed and more or less stay shut the fucked up when not wanted™.
I'm just talking function though, getting that within the existing construction may demand rehousing or unsightly modification, depending on existing conditions.