Hi @lewm
For that mod I'd recommend machining a new base pillar cap to be able to fit a cable retainer. You'd either need to solder the IC at the bottom of the base pillar, or run thin-guage wire the whole way through from the connection PCB in the base. The latter may not be ideal for a good many MM carts as the cable capacitance of such a set up would be rather high.
The mod I'm working on is a pillar cap so I can terminate mini-xlr, as I run balanced. That's more of a personal project as 1) I don't think many people would be interested in it and 2) it's something intersting that gives me an excuse to put the lathe and mill in the garage to use.