i´d also like to add it to my collection, because as it seems, i dont have a copy.
after a quick google search it turns out we should not need that for OS9... it seems to be for OS8... and you can also just use the startup disk controlpanel from OS 9.1 or higher to get the same feature (i.e. the boot manager screen) in OS 8... of course only as option when holding option. 
No, this tool is way better than what's in OS 9 (Startup Disk): It allows you to set OF firmware configuration from within the OS. This is epic! The bigger icons are also more comfortable to click on, especially if you configured to move your mouse super fast.
This is literally the boot selector used in OS X, but with extra Open Firmware goodness, and when booting to OS X, you can even set boot arguments! Very convenient! You can also create OF configuration files from this, and save/load them, all from OS 9.
I love this! Just confirmed it working on Mac OS 9.2.2 on the 1.5GHz mini. This particular mini model has also some additional boot problems sometimes, not seen in the gen1 G4 minis, so having these OF features made even more accessible is extra welcome for this particular Mac.
Thanks for sharing this discovery with us, @zefrenchtoon! This really needs a home at the Garden. It is not common knowledge that Mac OS X Server / Rhapsody has such interesting Mac-OS-9-compatible tools.