Mpc wont allow 4/6 time sig? work around?

Hi there
My song ive written in reaper is in 4/6 and i want to add beats from the mpc, mpc wont allow me to work in that time signature, other than working out what the bpm is in 4/4 does anyone know any tricks to get around this?
Cheers

4/6 is not a real time signature - that would require 4 "6th" notes per bar. Maybe you mean 6/4? It should let you do that.