>> I tried the latest GENERICSBC (29 as stated above) on my 
>> PowerBook 520 in order to figure out whether the sn driver
>> is working. Unfortunetely it hangs while booting. I can boot
>> single-user without any problems. But if I want to go multi-user it hangs
>> after:
>> 
>> [...]
>> setting tty flags
>> [...]

I was getting this error on my Powerbook 550c if I changed the /etc/ttys 
to read:

console "/usr/libexec/getty Pc"    vt220   off secure

If I changed the tty type (vt220) to anything BUT vt220, the machine 
would hang at setting tty flags. Have you made any changes? I was 
changing it to be vt102.  Big mistake. 

Steven Campbell