You can create a bootable USB flash disk that contains the Mac OS X Install DVD using nothing more than Disk Utility and an image of the DVD.
You need to ensure the USB flash disk is a single partition with a GUID layout (partitions tab will do all of this).
Once partitioned correctly drag the Mac OS X Install DVD image to the source field on the restore tab and the USB flash disk partition to the target field. Click restore and after a while you'll have a bootable Mac OS X Install flash disk.
I do this regularly with my Mac OS X developer image (DMG file) and it works every time. So much faster, more portable and great to also keep a copy of the latest combo updater.