The set up I use requires a long y cable that comes up each pant leg to the waist. Then I use a remote dual controller by Warmnsafe. The socks get plugged into the jacket (inot the little yellow plug) and the jacket (red plug) gets plugged into the bike. This setup allows separate control of the heat to the jacket and separate control to the socks. I mount the dual controller onto the back of the brake fluid reservoir.
My advice, don't get a single controller, because the in time you will find a use for needing another.
http://www.warmnsafe.com/dual-remote-control-heat-troller/
Here's the long y splitter cable if this is what you were looking for:
http://www.warmnsafe.com/long-splitter-cable-for-gloves-socks/