P2P and web surfing on 2 separate NICs

I am mangling good, high priority traffic (http,mail etc..) and low traffic (p2p, games etc..) on two queues, incoming and outgoing. Now I have just 2 NICs (local and public), but I would like to use a 3rd NIC and route high priority traffic on 1 NIC and low priority on another NIC.

Or another option is to have just 1 NIC (public) but 2 gateways connected on that NIC with 2 providers and then routing 1 traffic to 1 gateaway and teh other to the 2nd one.

Any idea ? how can I do it ?

many thanks
Gianluca

See Policy routing manual:
http://www.mikrotik.com/docs/ros/2.8/ip/route.content#7.48.4