I used a spare gondola (after converting the couplers to Kadee No.5s) to carry the battery (made for Airsoft guns) and CONVRTR chip along with wiring and a power toggle switch. I attached small plugs to the micro-Tsunami leads and two wires run between gondola and locomotive. I can explain in detail the set up more later if there is interest.
Note: There are no lights in the locomotive, yet. May not ever be, since they didn't operate at night, and several of the terminal railroads didn't require them. I'll have to check if that is the case on the HBS. This locomotive was a problem child, too, when it was just DCC, but it showed none of those signs in the initial run. That points to track pick up as the culprit, and not the Soundtraxx micro-Tsunami decoder. I was thinking that the 750 was getting overloaded and resetting, but apparently not.
I'll need to clean up the wiring now that I know it works, and I may try to put the decoder in the gondola, too, if I can't get it situated inside the locomotive. It keeps the body shell up off the chassis just enough to mess up the body-mounted coupler heights. I may be able to modify the motor enclosure enough that it will lay flat.
There will be a tarp or something over the "load" in the gondola, and the wires will be painted black and as small a gauge as possible. It should end up looking like hoses. The idler car works fine on the HBS, but the Erie 149th Street terminal doesn't have any spare room on a crucial lead.
The parts are not cheap, but then again, what is? The HBS will be an all battery fleet (5-8 locomotives), but the pocket terminals will probably stay DCC since there will be a variety of road names on numerous units - unless the shells are the only things that change...? ;)
For now, though: Oh, so happy I am.