If you simply want to slave one Fastrack Remote Switch to another such that when the Main switch throws the Slave also throws only two wires are required. On the underside of every track switch you will find a set of terminals to which the remote control is wired:
The terminals of interest are "THRU" and "OUT". Grounding "THRU" causes the points to be set straight and grounding "OUT" causes the points to be set for the diverging route. Two wires run from these two terminals on the Slave to the corresponding terminals on the Main track switch is all that is required. If the Slave needs the points to throw opposite to the Main just reverse which wire goes to "THRU" and which to "OUT".
Incidentally, the Main switch is also slaved to the Slave in that if a train approaches the Slave in such a way as to throw the points because or the non-derailing feature the points of the Main switch will also align for the train to pass safely through it a swell.