Here is where I saw the " *for use with optional NiCd batteries" for the transmitter:

http://www.helimax-rc.com/helis/hmxe04-index.html

I just looked into the radio again, and couldn't find any pins for a standard battery pack to plug into. So maybe you could just put 8 (EDIT: *rechargeable AA's) AA's into the transmitter and charge them through the charge port. The radio's futaba compatible, so I'd try a futaba charger instead of a JR one--I can't remember which of the two brands wires their charger plugs as center-positive, though.