I'd like to use a WMIC command in my SCCM 2012 Task Sequence to set UAC to the correct level. Can this be done? If not, what would be my best option during W7x64 deployment?
You can't set the UAC level via wmic.
There are a bunch of registry values that control the UAC level that can be manipulated:
Check this documentation out: https://msdn.microsoft.com/en-us/library/cc232771.aspx