Im not quite sure waht you actually mean here, but if you want to automate the plugin and make it wah your audiotrack, thats easy.
You can use audio and midi on the same track, so you
-open your wah effect on the same track as your audio,
-automate it by left-click the track envelope button (to the left of the track fx button) and choosing the vst parameter(s) you want to automate.
-now you should see the chosen parameter in the trackview as a line, and can edit the envelope by adding points to the line, by leftclicking.
If you on the other hand want to controll the parameters from an external controller, im afraid thats not implemented yet.
Hope that helps