OK, you're slightly restricted in how the AE Corner Pin effect works, but you can get the right result. If you have Red Giant Warp, you can achieve this without the Comp 2 step.
First make a new comp that has the same dimensions as the vertical screen. Drop in your footage and do the pan/scan here to select the right region. Let's call this Comp 1.
Now create a new comp that's the same size as the full frame (720p in your case), call it Comp 2. Drop Comp 1 in here, right-click it and choose Transform | Fit to Comp. What you should now see is the pan/scan region stretched to fill the whole frame.
Now drop Comp 2 into your main comp, and apply the corner pin effect to it. You should see it appear in the correct place at the correct scale.
J-P
John-Paul Smith | CEO | Imagineer Systems
www.imagineersystems.com
