Finally something i can contribute to on here! Well this is really late, but i hope it still helps. I have never messed with mohair, only horsehair, but the process is the same. I use a drill in a vice with the trigger tied so it rotates the speed I want it to. You twist the first strings CLOCKWISE, then put 3-4 of them together and twist them COUNTER-CLOCKWISE I'll call this a strand.( I don't like to use one of those separator things for this step, just let them twist on their own. ) Depending on how many hooks your mult-twister has (mine has 4) you make that many strands of 3-4 strings each. Now the fun part! you hook all of the strands on the drill at one end, and each strand on an individual hook on the multi-twister. The drill spins CLOCKWISE again, and the person running the multi-twister spins those hooks COUNTER-CLOCKWISE (this keeps the strands twisted up nice and tight) the other person uses a separator of some kind to control how fast the rope twists up. That's it!
So now that that is as clear as mud, check out "doug krause horsehair worker" on youtube, it will make more sense.
one really important thing is to have the tension the same on all the strings/strands as you twist them or you will end up with a crappy looking mecate!
my rope twister is an old sprocket off a baler, the small sprockets are the chain that i cut and welded together. it has a 6:1 ratio, so you don't have to crank so much! you can make some really simple multi-twisters that are only a 1:1 ratio, but they work really well.