Wonder if this applies to all Macs or just the MBAs?
B
I've done it on a Mac Mini 2011 with a bootable Windows 7 USB key. Made the USB key bootable using the command prompt: Diskpart.exe and then copying all the files from a DVD accross.
On another note: If you have a TimeMachine backup from LION then to restore (and have a totally blank internal HDD, e.g. after formatting it with Windows....) this TimeMachine backup: all you have to do is at boot time select the TimeMachine backup (should be green icon with option key) and it will give you the option to restore without the need for anything else.
If you have Windows installed then with Paragon Partition Manager you can create an Apple HFS partition and use TimeMachine to restore in that. That partition is then also under MBR and no conflict of GPT / MBR plus Windows is at the start of the HDD immediately followed with the OS X.