Building uEFI bootable ISO and USB for Windows 7 deployment
This Microsoft article covered exactly what you're looking for:
How to create an ISO image for UEFI platforms for a Windows PE CD-ROM for Windows Server 2008
The instruction line that is fundamentally different for UEFI images is:
oscdimg -m -o -u2 -udfver102 -bootdata:2#p0,e,bc:\winpe_x64\etfsboot.com#pEF,e,bc:\winpe_x64\efisys.bin c:\winpe_x64\ISO c:\winpe_x64\winpeuefi.iso