It depends what you want to put out there and how featured your window is. I’ve gotten away with making sure your blue screen is as far away from the window as possible and than adding some tracking markers in a few horizontal rows (try black gaff tape, or anything else that will be nice and visible in camera but not too large on screen). Depending on the shot you might not need much parallax and just tracking the points could be enough. Keeping your blue screen far away also minimizes spill on your set.
As an additional suggestion make sure you actually have glass or plexi in there – you can use the real reflections to your advantage and key through them with what we call a “soft matte” (basically just don’t key your footage all the way through, but spill suppress the hell out of it).
If the window is close to camera and your steadicam is going all over the place then you will need to do a 3D track as the other guys have suggested. For this I still suggest putting your blue screen as far back as you can, then add a few c-stands with bright tape or trackers on the ends of them at different depths outside your window (assuming the window is quite large in frame) this can help with your track if you don’t mind the additional roto/paint cleanup you’ll have to do.
Hope some of that helps! It would be good to see a still.
– Spencer