Thanks to another kind soul (and fellow ham), I was able to secure a copy of the developer's toolkit for the HE-232 (precursor to the CE-232) including sample Basic code. Whoo-hoo! Programming can commence!
The demo code that comes with the developers toolkit is written for QBasic, which used to come with every DOS and Windows computer. Alas, Micro$oft stopped shipping it with WinXP. But the folks over at the QB64 project http://www.qbasic.com/ make an updated version that appears to work just as I remember QuickBasic working all those many years ago. QB64 even created a compiled version of the code that will run as a standalone .exe under the WinXP command prompt. Back in the day, you'd have to pay M$ the big $$$ to buy a stand-alone compiler.
I took a quick look at the programming guide, and it's obvious this won't be a simple task to create software for the CE-232. I'll have to spend some time mapping out the program flow to learn exactly how this works. But it looks doable.