Murph, Where have you found the six connector wall plates (for RCA)? I seem to only be able to find 3+1 coax...
Bud
Sorry, I've been traveling but I see others have given you some ideas.
I used something very similar to this
7.1 wall plate for most everything but added additional RCA jacks for subs using a Decora plate
Like this one. that has room for an insert kind of like
six of these. except they had an F-connector on the back and were a lot cheaper than the ones I linked.
f-connectors are your standard coax (cable TV) conenctors. They are easy to crimp on to cable and they screw on so for a little added insurance for the side inside the wall. I went with RCA on the outside just as it's more of an audio standard but you could easily make a custom sub cable with an f-connector on the wall end and an RCA to plug into the sub.
Note: when you get into trying to tighten 6 f-connectors on one wall plate, it can get tricky as they are so close together. Requires some patience and it can help you spot if you are developing arthritis in your fingers, like me.