I found out how to add polygons to a person model! I spend some time with Bass-ti to figure out how to add new polygons to animated (person) models last week. I always thought it wasn't possible to assign new polygons to an existing animation, but I was wrong! I have modelled a new hat for the CHP officer and assigned the new polygons to the animation set of the head. I did it completely manually, that means using NotepPad to add the polygons of the hat to the person and assign it to an animation set.
Picture of the new CHP officer.

I am also going to make a new helmet for the SWAT units and soldiers in the LA Mod. It's also possible to add things like backpacks to any person model now.
I've made a 'tutorial' about how I added the stretcher wheels to the paramedic model. Adding a hat or backpack works the same way, except that you assign the polygons to an animation set instead of a dummy set (= not animated). If people are interested I can release this. Note: Learning this will be very time-consuming and difficult and I won't provide much support. It's (far) more difficult than learning scripting or moddeling, so it will be for advanced (3d-moddelers) only. Like Bass-ti said: "Scripting is like playing with Lego compared to this" lol.
Hoppah