Gave up trying to get Hyper-V Server 2012 to work…

http://blogs.technet.com/b/klince/archive/2010/09/13/booting-hyper-v-r2-from-a-bootable-usb.aspx

http://www.itstuff.ca/2009/12/create-bootable-usb-drive-for-hyper-v.html

• Boot Hyper-V Server from USB flash devices
• Saves hot-swap drive bay for storage
• 16GB Flash device recommended
  • Get the fastest one you can

1) Download and Install WAIK: http://www.microsoft.com/en-us/download/details.aspx?id=5753

2) Download the Hyper-V Server .iso file

3) Mount the Hyper-V Server .iso file (G: used here for mounted .iso file)

4) Open a command prompt as administrator:

diskpart

create vdisk file=c:\virtualharddisk.vhd maximum=6000 type=fixed
select vdisk file=c:\virtualharddisk.vhd
attach vdisk
list disk
select disk N (select the newly created VHD)
create partition primary
select partition 1
active
format fs=ntfs quick
assign
list volume (note the drive letter assigned to the VHD - E: used as an example here)

5) Leave that window open and open another command prompt as administrator:

“C:\Program Files\Windows AIK\Tools\amd64\imagex.exe” /apply g:\sources\install.wim /check 1 e:\