Controlling Soft Synths in Ardour via MIDI

Is it possible to control soft synths added as plugins in Ardour, using an external MIDI keyboard, either through a MIDI interface or via a USB MIDI device? I have both of these hardware connections, and they show up in qjackctl under the ALSA tab (not the MIDI tab).

Ardour 2 does not support Virtual Instruments at all. You will need to wait for Ardour 3.