I think the way to implement that idea on Nik's amps is to

1) Add HRM board to OTS.  From talking to him, the placement and screwholes are there, all you need is the board;

2) Remove pots on board and wire up to concentric pots on the front so you have T/M/B for both pre-V2 tone stack and post V2 tone stack, using concentric pots/knobs

3) Change the caps and slope values on the HRM TS board, thats presonal preference but I don't care for the values D used there

4) Have a push/pull to make the amp switchable from non-HRM (basically just bypass that tone stack) to HRM.