Hmmm. The zip extracts to .img files, which means I'd have to create floppies from those. I think I have a USB floppy drive somewhere, but even if I do, I'm not sure whether VirtualBox will suport it.
I've been scouring the internet for the native OS/2 version (which has the benefit of allowing Rexx scripting in addition to the value/event tree logic) but aside from a few references to it in passing, no one seems to have it, not even old software shops or abandonware sites.
So, if anyone does come across a copy of the native OS/2 version, I'd be very grateful if they'd let me know.