"smitty mkdvd" should work. If you don't have a dvd burner on the AIX server you can just create iso file(s) that you can copy to a PC with a dvd burner. You can specify the location of an existing mksysb image so it should work. I've only done it for cd's not dvd's so I can't speak from experience. But when making cd's the first cd is bootable.

One of my earlier posts details "smitty mkcd" which uses the same technique as "smitty mkdvd".