Power Mac 7220: BeOS 4.5 PPC
This was much easier than I expected. I had the original install media from purchasing this back in the late 1990s from The Software Shop in Phillip, Canberra. There's a boot floppy and installation CD. The floppy is not needed for the Macintosh.
Booting the installer
First step is to get the "bootloader" on your system. Once at your desktop, insert the BeOS CD and browse to Mac Tools. Drag the _bootloader to your System folder on your boot disk. MacOS will then store it in the correct folder for you.
With the CD still in the drive, reboot your machine. Thanks to the underscore at the start of the filename, the bootloader will boot as the first extension. You'll then get 1 whole second to select the BeOS icon. If you're too slow, then you'll be back at your usual desktop.
After selecting the BeOS button, your machine will either boot from a BeOS partition or the BeOS CD, if inserted.
Booting BeOS
If you managed to hit the 'right' button, then you should be presented with a beautifully-rendered 3D BeOS logo, in all its 90's glory.
After this, you'll get a standard EULA and then be presented with a very simple installer. Choose a disk (preferably a blank partition, so that you don't destroy valuable data) and then install. It'll take around 20 minutes.
NOTE: The PowerMac 7200 has an internal IDE HDD and CD. I couldn't get the installer to install from the internal CD. It'd boot from it, get to the installer and then sit on "Scanning Disks..." and then fail. I had to use my external SCSI CD drive to get BeOS installed!
Drive Setup is accessible from the Setup Partitions button and will let you mangle your disks as much as you need to.
And then you're set!
Pop the CD out and reboot... you'll be at the BeOS desktop as the boot loader remembers the last setting. If you want to get back to Macintosh, then you need to hit the Macintosh button on the boot loader within 2 seconds.
Anyway, nothing but natsukashi feelings once this loaded. I hadn't played with original BeOS for decades. Time to find some software that works!
Networking
BeOS kindly provided the driver for the network card that is installed in my Macintosh. It's a Communications Port II card with the DEC 21041 chipset.
The option is greyed-out in the shot above as I'd already installed it... either way, choose the driver that's appropriate for your card.
Have fun!