I'd like to install Ubuntu 12.04 LTS in OEM mode on a few desktops via usb drive.

These instructions work fine to install in OEM mode on a VM using the .iso from Ubuntu site : How do I pre-install Ubuntu for someone (OEM install)?

But as soon as I add that .iso to my USB the only option that shows up when I press f4 for the advance installation modes is "normal".

I'm using rufus to add the image to my flash drive and encountering this issue. I've also tried using unetbootin and I can't seem to get the advance installation options to show up by pressing f4.

Ideally I'd like to just make a permanent change to the boot options so the image boots in OEM mode since I will use this periodically for that purpose.

If that's not an option I'd be fine with suggestions for other programs that I can use to add the image to the usb and test to see if it will still have an OEM option.

Thanks in advance!