I think what I used to do, before I had a floppy drive was use Appletalk. Either the Outbound or the other Macintosh needed to be running System 7. Let's assume the other Macintosh is running System 7. Then use the Appleshare (IIRC) DA in System 6 on the Outbound (booted from Silicon drive) to mount a shared volume from the host Macintosh (can you share a mounted Disk Image? I think you can..).

It's been so long since I've done this. Anyway, it was fairly easy, using LocalTalk and AppleTalk File Sharing to boot the Outbound from the Silicon Disk, and then install the Mac OS to the hard drive, and then run the Outbound Installer on the hard drive. Then one could boot from the hard drive, and the installer should write the EEPROMs for the drive which is installed.