Uh-oh, something went wrong.
In my first approach, I compiled rxtx and just tossed librxtxSerial.jnilib into the Arduino directory (regular version 03 then). Java exceptions persisted, but programming the board worked occasionally (pressing RESET twice and stuff).
Now, in order to get the whole thing tidy and clean, I gave it a new try. Erased the Arduino folder in Libraries (the one with preferences.txt), then used the current macpro 03 release of Arduino, put in both librxtxSerial.jnilib and RXTXComm.jar from Processing 114 (in proper locations each), this time not using the files that I compiled myself. Ran macosx_setup.command from Processing (as suggested by Nick) and even restarted.
No matter what and how often I try, I keep getting "[VP 1] Device is not responding correctly." error messages. Tried it with and without setting download rate to 9600 in preferences.text, btw.
Isn't this the setup that works fine for most of you mactel guys right now?
My Wiring boards do still work properly on the mactel machine (same USB port), so I guess the FTDI driver is OK, too. The particular board I'm using can easily be programmed on a Windows machine, it's fine.
What might be wrong? I guess I need to start over once again... will I also have to get rid of the FTDI driver and re-install it?