WIRING TO AN MTH REALTRAX WYE

I want to wire from an MTH DCS system (TIU) to a WYE composed of an 0-72 Left turnout, a 0-72 right turnout and and 0-72 Wye.  These are all MTH RealTrax turnouts.  I plan to wire from the TIU to power this wye.  What connections do I need to make? (At what points do I attach to the center rail of this track arrangement?)