So I finally figured out how to boot my 7300 from a serial console.
It turns out that the problem I was encountering was a bad DIN8->DB9
cable I bought on the net somewhere.

Oddly, I had one of these beasts sitting in a drawer, from way back
when I first got a handspring visor with a serial connector kit.  At
the time I got the visor, I didn't know what that cable was for.

Here are the kermit settings that worked for me, maybe this can be
included in the FAQ:

define macppc {
  set line /dev/tty00
  set serial 8N1
  set speed 38400
  set carrier-watch off
  set flow-control none
  set modem type none
  connect
}

-russ