I recenly downloaded Darwin from Apple. In the distribution there is a 
program called "System Disk" which allows for a graphical interface to the 
NVRAM which is used to select the boot device and file. All editable, could 
be much easier to set up for using NetBSD. Since I'm still trying to set my 
G3 up to run BSD I am only guessing that it could be a valuable tool to use.

Rob