Got it done!
The sleeve is put through the hole in the bottom of the window first, then the plastic pin is pushed in second, so that both are about equally spaced on either side of the window. Then, the glass is slid in to the door and in to the regulator's plastic lift guide and a bit of a force is applied to snap the plastic pin/sleeve on the window over the lip of the regulator's plastic guide and in to the hole at the top of said plastic guide.
It is a little bothersome to do this because that plastic guide is usually the sole failure point of the regulator given its plastic condition, so one would think this area would be made of a strong material, given installation directions of the glass and regulator require one to add a bit of force to seat the glass in to this part of the regulator.
Now, to find a way to replace the plastic guide on my removed regulator to keep it as a spare.