I should also note that I'm trying to add a few files in a folder called "Mac" to the iso (in MagicIso) before burning.
This is the problem.
NEVER use an ISO editor for bootable CDs. Always create the iso again with mkisofs
. You get the checksum error because the isolinux.bin (boot loader) file needs to be patched, so it knows its location on the ISO. This patching is done by adding the "-boot-info-table" parameter to mkisofs.
Extract the UBCD501.iso to a dir named ubcd-extracted.
Add your Mac folder in the ubcd-extracted dir.
Open a command prompt and cd to ubcd-extracted.
Run the following to generate the iso:
mkisofs -iso-level 4 -l -R -J -joliet-long -D -V "UBCD501" -o "../ubcd501-custum.iso" -b "boot/isolinux/isolinux.bin" -c "boot/isolinux/boot.catalog" -hide "boot/isolinux/boot.catalog" -hide-joliet "boot/isolinux/boot.catalog" -no-emul-boot -boot-load-size 4 -boot-info-table .
You can also test the ISO first in a virtual machine like VirtualBox, to see if the ISO boots.
Download Ultimate Boot CD v5.0
Use Parted Magic
for handling all partitioning task: http://partedmagic.com/