I just replaced the seals on both of my vent windows last weekend, and the way I got the glass out of the frame was to drill out the two rivets that hold the outside pivot to the frame. After that you can pull the glass, replace the rubber seal and then rerivet or bolt the outside pivot back into place. I used a couple of 4-40 bolts on mineand the only trick was that you have to pull the rubber back out of the frame in the area near the pivot in order to get a small screwdriver in. Hope this helps.
Richard