In other apps there is a Corner Pinning effect to distort or undistort images. And I had some footage that was shot with a very wide angle lens. I tried the undistort node but found that I could not correct all the corners, as the shot was a bit skewed to one side.
So I made a simple plane object in the 3D view and unwrapped it. Then subdivided it, making sure to place verts in the middle as well as at the corners. Then you go to render layer settings and activate the UV pass.
After rotating the image and applying the undistort node I take the output from the scene layer using just the UV pass.
I can interact with the compositor by modifying the plane and hitting F12.
Here is the layout of nodes with the after effect in the middle.
I guess you could also add a vert hook there and change the UV dynamically, perhaps from a tracked feature?