You're not going to be able to simply run a 3.5mm cable from the SR out to the connecting block.

Xantech makes a model 794 interface that's designed to interface IR products with the serial control jacks on various brands of electronics which may work, but if I were you, I'd call the Xantech tech support folks and pose the question to them to make sure that it's going to do what you want it to do.

Their technical application guide mentions that it works with Pioneer, but it specifically mentions the multi-room control out and not the standard SR.