Hey
I think you need to have an optical drive in order to install the main program 8.0 LE as the updates needs the drive CD to react to but you can try this page and see if you can use the full installer here:
http://secure.digidesign.com/service...rticleId=43353
Post back if that doesn't work as I still believe you need a separate optical drive to install the CD first.
Best of Luck
Christopher