Ahh.. I get it. upgclient.static works only with the default "/dev/ttyS0", not when using the "-p" parameter to supply a different path. I can create symlinks in /dev/ to get around that, though.

Like download.c, it fails on the wired USB serial ports I have here. But it does seem to be doing *something* over the bluetooth AIR-cable serial port I have, which normally does work okay with (my modified version of) download.c

But it's very slow right now, whatever it's doing..