I have the CT-1 and CT-4 (same power, same batteries). I modified mine to use the alkaline holder but feed the current in the Ni-Cd/NiMH circuitry. It involves opening it, de-soldering two wires and soldering one back. Any competent electronics enthusiast can do it for you.
NiMH work on the alkaline circuitry, but due to the lower voltage the max power will decrease by a bit. If you don't need max power from it, use it as it is.

Btw, congrats on the choice, you will not regret it