I have mine setup like this
B?XEC-DVDPLAYER\dvdplayer.elf = Free McBoot v1.4b osdmain.elf
B?XEC-SYSTEM\osdmain.elf = Free McBoot v1.4b osdmain.elf
mc0:\BOOT\BOOT.ELF = ULaunch v4.16
mass:\BOOT\BOOT.ELF = ESR beta vr8a dvdv direct.elf this means when I have a dvd-v inserted it'll automatically boot the backup if I take out the usb stick it'll load ULaunch 4.16 instead, whilst running ULaunch load ESR beta r8a mcard.elf that'll in turn boot mc0:\BOOT\BOOT.ELF which will give ULaunch access to the dvd-v files from there load HDLoader v0.8cp.