brain jr. and a mixer diy

hi there all just been noseing at some home made midi controlers, just a quick question lol

i have a dj mixer that is fully working and i was wondering if i could slip a brain jr inside it and attach another three wires ontop of the crossfader wires and feed them into the brain, will this stilll work as a normal crossfader and send simultaneously signal thru the mixer and  to the brain jr for mapping on the pc in ableton,traktor
many thx