There are a couple of flaws, though. First, you'd have to build six PCBs and figure out how to fit them into the M-1000's housing. Second, you'd have to rewrite the firmware - and add some more CV multiplexing. But well.
Still, I think tinkering with the M1000's hardware and firmware is well possible. I've started collecting the basic knowledge in a Google Doc - have a look, and if you'd like to add something, comment.