the New-VMHostNetworkAdapter offers the ability to set the MAC address while adding a new kernel interface. But this has a limitation. It always only a MAC within a range 00:50:56:00:00:00 – 00:50:56:3F:FF:FF.
If you try it even though you will get an error:
New-VMHostNetworkAdapter The MAC address is invalid or is not in the valid range 00:50:56:00:00:00 - 00:50:56:3F:FF:FF.