I got an Evolution 449C for Christmas so I just read the manual
It would be like:
Computer <--USB--> Evolution --MIDI--> Virus --MIDI--> Computer
Plug the Evolution into your computer using USB, that takes care of controller -> computer.
Plug the Evolution MIDI out into the Virus MIDI in, that takes care of controller -> computer.
Plug the Virus MIDI out into the sound card MIDI in, that takes care of Virus -> computer.
Since the Evolution can also act as a USB MIDI interface, you already have the computer -> Evolution -> Virus connection, although it may be better to just physically switch the cables when you're doing much work with the Virus and computer, I'm not sure about latency of the Evolution.
EDIT: Also, I *think* your sequencer should be able to route controller data through the computer to the Virus if you want to do something like:
Virus <--MIDI--> Computer <--USB--> Evolution