Here is one of my old DDE files for a Ghost/Emergency Recovery boot disk I still use. They are just text files.
CODE
; DIAMOND Directive File (.ddf)for EBD.cab
.OPTION EXPLICIT
; Generate errors on variable typos
.Set CabinetNameTemplate=EBD.cab
.Set Cabinet=on
.Set Compress=on
;The files specified below are stored, compressed, in the cabinet file
ASPI8DOS.SYS
ASPIPPM1.SYS
ATTRIB.EXE
CHKDSK.EXE
DEBUG.EXE
DOSKEY.COM
EDIT.COM
EXT.EXE
FDISK.EXE
FORMAT.COM
GHOST.EXE
GUEST.EXE
GUEST.INI
HELP.BAT
MODULE.INI
MORE.COM
MOUSE.COM
MOUSE.INI
MSCDEX.EXE
NIBBLE.ILM
NTFS_MAN.txt
README.TXT
READNTFS.EXE
RESTART.COM
SYS.COM
XCOPY.EXE
;The files specified below are NOT stored in the cabinet file
;DRVSPACE.BIN
;SCANDISK.EXE
;SCANDISK.INI
Also see
Microsoft Cabinet Software Development Kit