After failing to get the tools in the OpenDJ SDK to work on Windows, I decided to try just unzipping the latest server distribution (2.5.0-Xpress1) and trying my luck with it. Turns out it worked right out of the box.
I still haven’t figured out what’s wrong with the SDK snapshot, but to get the same functionality out of an unzipped copy of the Xpress1 server distro all I had to do was a “set PATH=c:\apps\opendj\tools\bat;%PATH%” and it just worked (that being the path to where I unzipped the distro). No running setup necessary (or desired).
So far everything seems to work as it should, although I haven’t tried anything fancy like dsconfig (well, I did try the control-panel applet — and THAT worked too — at least connecting to a 2.5.0 server, it wouldn’t let me connect to a 2.4.5 instance).