Brain Jr question

First of all when are they expected to be back in stock? Also I want to make  a Midi controlled single pole 3 position switch when the switch is in the middle the value of the switch should be 50 and when moved to the left it should be under 40 and when moved to the right it should be over 82.

I assume all of this can be done with sysEx? I'm new to trying to figure this out so I don't know how the code should start out.