i dont think this will be there for virtual machines...there is one for the network traffic mirroring, again this is different... can you tell me what is your objective... and what you are going to achieve.?
there are only 3 modes of tagging in the esx.. VGT,VST,EST...this covers almost all the use cases.
ERSPAN
The encapsulated remote (ER) SPAN feature enables users to monitor the virtual infrastructure traffic across an
IP network. Traffic to the remote monitoring device is sent through an encapsulation envelope, also referred to
as a GRE tunnel. As shown in Figure 2, the ERSPAN session is configured from the VDS to a remote monitoring
device across an IP network. The configuration steps involve choosing the destination IP of the GRE tunnel. The
orange broken arrows show the GRE tunnel established between the two endpoints and the mirror traffic flow.