Agree with JoeMc !!
Tape everything ! I actually used duct tape over the masking tape so it wouldn't tear through. If I remember correctly, you have to put the edge where the arched slide is in through the widest opening in the quarter panel . Then, rotate the assembly until the geared section clears the quarter panel opening. Finally, rotate the window track into position. Also, I found it easier to leave everything relatively loose until the glass is installed in the track. Hope this makes some sense as it hard to describe the procedure!!