If I were you I'd try to have a look at how the weapons in FPSC are constructed and animated before you start trying to import your own.
I've been looking at them in Fragmotion and there's nothing simple about how they're setup and animated. The manual doesn't really cover this kind of thing too well.
Even the static entity's may require some tweaking before they'll work.
Copying the scripts from other entities will be okay, but unless you know what your doing it could lead to a lot of frustration.
Not trying to put you off, but unless you know FPSC well or can get someone to help you it won't be as easy as "putting the files in the right directories".
instinct is more valuable than intelligence.....