NetFlow generator. Howto separate VLANs

NetFlow generator. Howto separate VLANs

hi!
We're testing Netflow.
Our switches (Cisco 3750G) doesn't support NetFlow feature, so we're trying to use NetFlow Generator.
We've mirrored a couple of VLANs to it and we CAN see a traffic.
The question is: is there a way to divide or separate traffic by VLANs via NFA or Generator?