Hans> I created my own boot cd using Toast on the Mac.
Hans> I included the following files:

Hans> macppccd.iso
Hans> ofwboot.xcf

In the INSTALL.html, there is a instruction how to use Toast.
--------------
 -   From a MacOS machine (using Toast)
     1.   Open the `Format' menu and pick `Disk Image'
     2.   Click the ``Data...'' button and select the disk image you
          downloaded.
     3.   Click the ``Write CD...'' button
--------------
Did you follow that part ?
I don't think you need to put ofwboot.xcf.
It is included in macppccd.iso CDimage.

Good luck,
---
Makoto Fujiwara
http://www.ki.nu/software/NetBSD/iBook2/