Question How do you load other assets from other levels in MW2? (Weapons, Models, maybe sound but idk about sound)

[extundo020202]

I have always been curious as to how some people had been able to take other assets from other levels and load them into one that doesn't have said asset. I am wondering how this may be done. I do know some modders say they have tools for that but can't release it to the public. Are there other ways?