I was also interested in this and at least one of the members has a working MPCNC on the Ender 3 board:
I can’t help out much more than that as I haven’t tried it yet, I am still building mine and the Creality board isn’t suitable for me as I want dual endstops. I’ve ordered a SKR 1.4 Turbo, which has 5 motor drivers on it… just waiting for it to arrive via the slowest ship ever.