Feel stupid asking, but in all the years I owned my car, I never had to mess with the headlamps. I took them off to repaint the grilles and was wondering if there was a special trick or process to get the stainless trim rings back onto the assembly without disturbing the headlight aiming/adjustment screws. There is a lot of pressure on them due to the springs that attached to the trim rings. Or is there a special tool to pull the rings out far enough so they can be screwed back on?

I've not run into a problem like you describe. If you haven't found a way around this here is my suggestion. First be sure not to change the settings on the larger screws which are used to aim the headlights. There are three screws on the headlight retaining rings. those are the only ones to take out. Next,
Harbor Freight sells little picks with straight and curved ends and I think they are less than $5 for a set of 4. I've found these very helpful and I think you could use them to carefully remove the stainless headlight rims once the screws are out. I would pry through the holes for the screws that were removed. A final thought if you have not messed with the headlight aiming screws is to park the car with headlights shining on a garage door. Put a cross of painters tape on the door in the center of the light shining on the door from each headlight. After you change the bulbs, if the headlights don't center on your tape marks, use the adjusting screws to get them back where they were. Finally, if you did change the aiming, I'd just go up to a garage door, turn on the lights and adjust them to where it looks good. Hope this helps.

Ha, funny, I just got done doing exactly what you described. got a 90 degree pick to hook into the trim ring slot and was able to pull the trim ring over the headlights. Lots of resistance in those springs, but it did work without changing the headlight aiming/settings. Thanks.