okay,
1) You should not have put that pizza option in the poll. Because of that most people will vote for that option and not take your idea seriously. (If you obviously don't, why should we?)
2) This is not possible with scripting.
3) The idea sounds fun and probably would look cool, but it just utterly pointless in my opinion. A waste of time MM could use to fix bugs and add better new features.
Why not just fix the Soldat code for the Weapons.ini so if you rig the nades as "shooting" bullettype = flamer flame then you'll get a flam0nade instead? =.=
huh. Someone try this and see what it does.