How to log this virtual cache:
Step 1: Do all the standard geocaching stuff of setting waypoints and wandering around until you find what you think is the proper location. If you don't find pavement that is uneven, then you haven't found it. When you find it, there will be no doubt that you are in the right place. Don't go at night as there isn't enough light after dark to capture a good image.
Step 2: Contact a co-conspirator who is at an internet-connected computer and send him/her to http://www.tour.pitt.edu/h_cam.
Step 3: Have your co-conspirator click on the "Start Control" button. If someone else was using the cam, the wait will be about three minutes before live panning access is granted.
Step 4: Once control is gained, have the co-conspirator pan the camera around until they find you.
Step 5: Pose for the camera. Your co-conspirator has a lot of control in panning and zooming so they should be able to get you in the center of the frame. If you are in the right spot you are unlikely to be in a crowd of people so waving like a fool or holding up your GPS is not necessary. Merely looking at the camera should be good enough.
Step 6: Have your co-conspirator click on the camera icon at the lower left of the window. This will create a new pop-up window with the image. Have them right click on the image and save it to disk so that you can upload it later when you log the cache visit. It will be a 320 x 240 BMP file.
NOTE: The webcam is owned and operated by the University of Pittsburgh and, other than Pitt being my alma mater, I have no affiliation with the university and have no control over the cam.
Extra Bonus Challenge:
There is another camera atop the Cathedral of Learning and this virtual cache is visible from there. Goto the camera at http://www.tour.pitt.edu/cl_cam.html instead of the one above and take a picture. This is a little more tricky as the camera is further away and it could be a little more difficult to direct the co-conspirator. Also, being so high up, winds tend to buffet the camera.
Spoiler:
If you really want to see where I was standing when I took my GPS reading, visit my geocaching website at http://www.tasigh.org/gps/index.html. If you look here before trying to find it with your GPS, you're in the wrong sport. Once you've logged your site, compare it to where I was standing to judge the precision of your (and my) GPS.