I'm actually surprised that with 802.1x you are not able to get the NAT feature of VMWARE to work.
So let me explain.
With UAC you get two different types of enforcement.
1) L2 (802.1x) enforcement
2) L3 (source ip/IPsec) enforcement
With L2 enforcement, all that is required is that you have supplicant software on your workstation. You can use OAC or you can use the Microsoft Supplication software (wireless zero config). Once you have completed the L2 authentication, the switch will open the switch port.
So if you've authenticated with the host system, I would imagine that any of the VM's using NAT should be able to connect through the now open port. OAC, for L2 enforcement, is only active during authentication.
L3 works a bit different. L3 enforcement is done by an Infranet Enforcer. If you are using Source IP enforcer, then you should be find connecting from NAT clients on the source workstation. If you are using IPSec enforcement I would bet that it may work since the VMware network stuff should just follow the Windows routing table.
I've not tested IPSec but I've had no issue with L2 or L3 (source-ip) enforcement.