I know that a lot of people have been waiting for a solution to the capslock/control problem under Panther. Well ... I just finished modifying the keyboard driver for the G4 PowerBooks (it may well work on other ADB keyboard machines). This driver will map the capslock and enter keys to control.
Download the installer [415KB download]. The installer will install the driver to your system. Inside the installer package is the source of the new driver, and the diffs with the stock Apple driver.
PLEASE read the messages in the installer before hitting the install button!
[robg adds:I have not tested the new driver, but I know people have been waiting for it, so here it is. Since the source and diff files are included, it should be easy to verify that nothing bad is happening with the modified driver. According to the author, this should work on Jaguar as well.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031102032521826