1. Compile up a kernel that works on your system.
2. In the top-level directory of your kernel source tree, do
   "make vmlinux.coff".
3. Get ftp://samba.anu.edu.au/pub/linux-pmac/install-source/ramdisk.image.gz at ftp://samba.anu.edu.au/pub/linux-pmac/install-source/ and put it in the arch/ppc/pmac/boot subdirectory.
4. In the arch/ppc/pmac/boot directory, do
   "make TOPDIR=../../../.. vmlinux.coff.initrd".

The vmlinux.coff.initrd file is your new installer.coff.
Paul.