I have a MacBook Pro, and I was able to "burn" my Windows 7 ISO onto a USB stick, boot from it, and install it onto a Boot Camp partition. Now I'm trying to install Windows 7 on my friend's iMac, but his entire system seems to be staunchly opposed to anything to do with booting from USB (I actually had to modify the Info.plist file within Boot Camp Assistant to even enable the "Create Windows 7 bootable USB" option). The USB device does not show as an option in the Startup Disk section in System Preferences, nor does it show up if I hold down the Option key while booting.
It's clear to me this is one of those arbitrary Apple-imposed restrictions and not actually a bug. I'm looking for a way to get around it.
My MacBook Pro: mid 2012, MacBookPro9,1, 10.7
His iMac: mid 2011, iMac12,1, 10.8