Easy2Boot has its own fast USB 2 driver - did you try it?
Just hold down the SHIFT key as E2B starts to boot - you should see some sort of message about USB device 0x80 if it works.
The other alternative is to use Plop! burned to a CD - you boot from the CD and then it boots from the USB drive...
Do you mean that you get the 'A required CD\DVD drive device driver is missing' message?
If so, the problem is that Setup cannot find the \Sources\Install.wim or .esd file on the **USB drive** and NOT that it cannot see a hard drive.
When E2B boots the ISO, you should see a blue console shell...