Something that, for me, was difficult to find was how to create the ISO. Here is the command I used; hopefully it will be helpful for others.
First, copy all the files from the openSuSE boot cd to a directory, here called suse/ . Then replace the openSUSE-11.0-read-only.i686-2.7.0 file on there with the one that you created. Then run the following command:
sudo genisoimage -b boot/i386/loader/isolinux.bin -c boot/i386/loader/isolinux.cat -no-emul-boot -boot-load-size 4 -boot-info-table -l -R -r -o opensuseboot.iso suse/
This will name the outputted image "opensuseboot.iso". Some comments on the options:
The -b and -c options give the boot image and boot catalog. The files need to be in relation to the ISO's root, not your current working directory.
-l allows long filenames
The -R and -r options set things for the Rock Ridge protocol.
Hope this helps!