Tips to install Windows 8 pro to a tablet using usb and a mac?

Problem: I have Windows 8 PRO needing to be installed onto my Acer Iconia W 500, and what I have is:

- USB stick

- Windows 8 pro CD

- A 2008 mac running OS X 10.5.8

- A acer iconia w 500 running Windows 8 Release Preview build 8400

The tablet has no DVD drive (of course), and I don't have an external one.

I have managed to create an ISO image that works on the tablet, but if I start the process on desktop, it claims I don't have enough space, even though I have more space than is required. If I try to get the tablet to boot from the USB, the tablet goes straight to windows, even though I have changed the boot order to boot from the USB first.

Any help/suggestions would be welcome.