I'm currently at CES.
I have a sketch describing what the industry standard is for these jacks. I spent a good deal of time talking with an engineer today about that very question.
I had metered out the jacks while they were on the board by plugging in an 1/8" to RCA splitter, then again when the jacks were desoldered.
I did find out that it's standard to do an auto muting on these jacks because if it's left open and there's nothing plugged into the port, there will be a good deal of noise.
As for what cable to use...we will be getting an extra cable that's the same as the RCA cables we will be using. With this cable, we'll cut it up and make the 'jumpers' to go from the board to the RCA sockets. Hope that helps!