If it's anything like the script in SA, yes it's doable. The script for P&S is similar to TF, etc but there's issues.-
Models. If you want to "tune" the cars like SA you'll need models of the parts & the cars will need to be made to
support them (body kits, spoilers, etc). Typically GTA engines only support so many models (buildings, cars, peds,
trees, etc). There should be wheels already available as they are typically separate models called by one of the
DATA files.
Once that's addressed you'll need to setup an interface, even if you just want to select your colors. Then you'll have
to make the DATA files related to the garage.
Suggest leaving this one to the seasoned vets.