after a quick look at the "Montreal Controller", it appears to be a pic-controlled system. I didn't see any remote controllability. That's been a high priority for me. I just finished assembling two additional UV-3R/piccon foxes for tomorrow.
I had some difficulty coming up with the power connectors and 4 contact mic plugs, then it occurred to me that they already come with the HTs, so I just clipped them off and used them. (off the charger and the earphone accessories) The wire in the earphone is about 10 strands of #30'ish enameled wire, easiest to just cook it on the iron a few sec to burn off the enamel before soldering down. Still pretty frail, but doable.
The radios were $35 ea on ebay, the piccon was that much again. Toss in a toggle switch, 8 AA rechargeables, a buck-regulator from ebay ($2.50) a battery snap and holder, a DB-9 male, some wire, tab of tape, and a couple wire ties, and you've got a very decent complete fox for about $100. (without enclosure, but creating THAT is more of an "art") I set the reg to produce 4.4v, the UV-3R claims to see 4.1. Using 8 AA gets 10v with rechargeables, and should easily run all day, and without changing characteristics.
Radio Shack does carry the 2.35mm power barrel connector, surprisingly. It's not where you'd expect. It's one of the heads for their multi-use power supply, it's head type "A". (they get over six bucks for it though) So getting the power barrel or the mic plug the usual way seems expensive. I just harvested from the included accessories on these latter two foxes.
You can wire up your piccon to the UV-3R without buying an expensive cable. Din-5 goes to tip, din-1 to ring 1, din-3 to ring 2, din 6 and ground go to ground ring, din 7 goes to V+. The UV-3R won't work properly with more than 4.7v power in the adapter plug, and the piccon needs a bit more, so you can either run a regulator like I did (cheaply from ebay, I got a 10pk, was surprised to not have any noise) or use a 9v battery for the piccon and a 4.5v battery holder of AA, C, etc, for the UV-3R. (or just use the internal battery, but it's only 1000-1500mAh) I prefer to use AAs, something that's high capacity, easy to change out, and can sub in alkaline in a pinch.