Depends on what you need, if you want a simple setup some folks use a midi mouse..this works only for midi program changes, I believe.
For midi midi CC you will need something more complicated, I have tried and used :-
1. Rocktron MidiMate … Found it complicated to program and you can not do tap tempo on the Factor pedals.
2. ground Control Pro … Really easy to program and worked very well
3. Fractal MFC-101 very configurable and lots of switches… Probably too much if you are controlling just the two factor boxes