In the v6.0 release notes, fixed issues there is:
NX-2437 (Ability to change MAC address on an interface)
How exactly would I do this? I have a couple old devices with interface MACs coming in as 00:00:00:00:00:00 and would like to set manually.
NX-2437 only adds option to change MAC address for interfaces that were created manually, so guess this won't work in your case.