I haven't gotten time to mess with Reloaded since I got back a couple weeks ago, but my guess is you should be able to replace the stock files with Reloaded ones outright. I can't recall if the model files contain any other information; if they do, that wouldn't be an option. In which case, you'd need to extract the model info and then plant it in the stock files. Check out the models section for a walkthrough of how to import files; hopefully you'll be able to figure it out.
Sorry this is so vague. I'd try it out and then tell you how to do it, except I'm moving across the country and starting college. Don't really have much time to experiment at the moment. If you don't have it down in a couple of weeks, I'll see what I can do...
