Moving The MDT Wizard Off The Boot Disk
Jason put together a nice post that discusses moving your custom files off the boot disk to a network share, so that you can update your files and not have to create new a boot image every time.
Read more here:
http://myitforum.com/cs2/blogs/jscheffelmaer/archive/2010/02/11/moving-the-mdt-wizard-off-your-boot-disk.aspx