Does Intel vPro work via add-on NICs?

vPro utilizes the integrated network adapter. Currently add-in cards (fiber or otherwise) are not supported. However if they are willing to use multiple adapters they could user a fiber add-in card for high-bandwidth traffic, and a second wired connection for manageability.

Source: http://community.spiceworks.com/topic/116384-intel-vpro-and-fiber-networks

I would try using a media converter from ethernet to fiber instead of another card if you want to connect via fiber and use vPro.