Network packet Analysis sensor - does it work on a cisco span port?

Hi

I am trying to deploy a dedicated network packet analysis sensor in NPM11. I am spanning our internet link on a cisco switch. When I set up a monitoring machine on a spanned port I usually have an additional nic card so I can still access the network as monitoring a cisco port puts it in a sort of down state. I cannot use the network packet analysis sensor with one nic as the port is in the down state when spanned. I also cannot see a way of using 2 nics and telling solarwinds to capture from the nic connected to the spanned port. Any help would be really appreciated.