Nameloc, I thought it was pretty clear to you and everyone else here that the supply voltage that is going out the mics on the hot wire is somewhere around 10 volts, when you use phantom adapters and a PS-2. (or any other phantom source for that matter)
Therefore, it is very simple to (almost) replicate this same power with a "3-wire battery box". It's just straight supply voltage. The only difference is that the power is unblanced, but for 4-5ft of cable, it doesn't matter.