after spending like 20 minutes attempting to mount 1 damn sipp socket on the ribbon cord ... I've decided I'm spending the money and getting solid core wiring of some sort.
# I kind of disagree with the way you are going about cutting the grooves. I also don't think that a mitre saw would help either, you'd really want a circular saw, table saw, or a router for what you are talking about. Of course the cheapest of these options is the circular saw. You can set the depth, then make a number of small cuts (as deep as they need to be) across the length of the joint. Then a chisel and mallet can remove the 'fins' from the wood. Don't get me wrong, you could do it how you mention, but I think it be easier the way I described.