If you want an initrd loaded, you will need to configure it in Penguin. They get loaded off the MacOS disk into RAM by Penguin, which then just passes addresses to the kernel.
OK, that's the way it is configured.
On the mounting root from a SCSI drive, are you 100% sure about your root being on sdb4? In my experience, mac partitioning forces you to have
It is sdb4 in 2.2.25. sdb1 is partition map, sdb2 is mac driver, sdb3 is swap and sdb4 is Linux filesystem. MacOS is on on sda.
Should probalby try and capture serial console output to investigate more.
-- Meelis Roos (mroos@linux.ee)