I bought a FCB1010 to control two KP3 with its 12 footwitches (FW) but I have only one KP3 for the moment.
I used an old SCART cable (with a lot of wires in it ^^) with a male and female plugs for separate the units easilly.

On the KP3, there are holes for each buttons to solder wires which will be linked to the FCB : footswitches 1 2 3 4 to loop bank 1 2 3 4, Sampling button to FW 5 and Tap tempo to Down FW.

I have left unused wires for another KP3 =)
Here is a little demonstration, there is no music ^^
http://youtu.be/rkvIHdAQ-58
CyA