Is a bit of a hassle. I used the create task sequence media to build the media. I ran into two problems:
Failed to create media (0x80070057) CreateTsMedia 2/5/2013 2:07:35 PM 2540 (0x09EC)
Format failed (0x8004242D) CreateTsMedia 2/5/2013 2:12:44 PM 2756 (0x0AC4)
The first resulted from having both a mapped network drive and a hidden drive without a drive letter assignment.
The second happened because I am trying to use a 64 GB USB key and ConfigMgr does not support that. Kind of ridiculous.
sel dis #
cre par pri
sel par 1
shrink desired=32768 minimum=32768
format fs=ntfs quick
the magic line is shrink desired=32768 minimum=32768, works now in windows 7 !