There's no reason that it wouldn't work electrically. Those remotes are fundamentally just a two-stage switch in pretty packaging. I can't speak to how much room there would be for the required battery for a CHDK remote.
I bought my Promaster remote presuming that I needed the proprietary Canon 3-pin connector. I was incorrect. As such, I don't need the remote. If you want it for testing, it's yours. It's got a 2.5mm stereo female output.
That being said, I've got something that may be of more use to you.
I've got the transmitter half of an Aputure remote release setup. It's the thing mounts on the camera in the left half of this picture:
http://www.aputure.com/en/images/Product_banner05_1207.jpgIt's got a (cold) shoe mount on the base, a 2.5mm female jack, a switch, an output LED (on top), a two-stage switch, and a 2xAAA battery compartment in the back. Although the 2xAAA may not give the voltage required for a CHDK remote; you may be able to reuse the space. Perhaps 3xAAAA? I don't know the preferred battery for a CHDK remote.
Either / both are yours if you want them for experimentation.
