"Can the Torx screws used to allign the headlights be changed without changing the entire headlight assembly?"
Yes
"If so, where can they be purchased?"
They seem to have part numbers. Maybe your local Mopar parts counter can supply them. The up/down screw uses a clip. The left/right screw is different and doesn't use a clip.
The following are part numbers to try:
6033375AB SCREW, Special Head, . 218-28x2. 44
55054856AB SCREW, Aero Headlamp
6033376 CLIP, Lamp, Aero Headlamp Adjusting Screw
The parts book shows the numbers but doesn't illustrate these particular parts. The head lamps are very easy to remove if you haven't already done so.