Yeah after some searching around: it doesn't exist .. not for guitar anyway, and indeed anything other would probably be of lower quality. :(
I'd rather replace a tone pot with a kill switch.
I know, I have a mini-switch in there now. I want it closer to hand though but I need my volume pot to I'm stuck.
It's in an Ibanez S470DXQM, 2 holes only, and I'm not drilling any more ;)
Aw well, it was a nice dream. Maybe someday it will catch on haha, it would be nice for all those one-pickup-one-knob guitars. :)
As for modding a push-push .. I think it would be possible, but it would require a large amount of luck to get it back together and working properly.. (and reliably). :(