all you need is that switch...and you might already have it.
the switch actually gets "pulled" backwards when it is in the neutral position. that triggers the mirrors to fold or extend.
depending on the wire harness, you will need to run a trigger wire from the adjustment switch to the mirror. relatively easy though.
btw, when you install them, there is a synchronization procedure inside the owners manual. make sure to do this. it sets the power fold mirrors up so they fold and extend the proper amount and do it in sync