Maybe this is possible now, I'm still working through the documentation but nothing is popping out screaming that this feature is supported.
What I want to do is make a piezo,piezo,piezo,switch snare.
I want the first two piezo's to be head velocity and rim.
I want the third piezo to be nothing but positional reference.
I want the switch for a capacitive sensor switch that when closed, causes the rim to send cross stick.
I doubt any other module would/could ever support this but I figure with megadrum there is a possibility. you already allow combined inputs for roland dual input 3way cymbal pads, this is essentially the same thing but for the snare. Further difficulty is using two different piezos for the head.
My ideal snare then would be ATV style triggers around the edges. Bar across the middle with both the center positional piezo and the rim piezo with some sort of elevated platform for the capacitive touch sensor. If you already have this feature or could add this feature I'd place an order today for a 56 input.