Yes, most usable items ultimately cast a spell. There are a host of item property 2DAs that intermediate between the item itself and the spell scripts in spells.2DA. They can be tricky to understand and manipulate, but once you get the gist of them they allow you to create entirely new item properties.
I created a bunch of new alcohol types with different effects by hijacking the standard alchohol drinking script, and having it search the item for a local variable. Piggy-backing off the standard scripts is generally easier than creating entirely new item properties.
If you don't like the thought of editing 2DAs, then you can also use tag-based scripting to have items run your own set of scripts. There's bound to be a tutorial somewhere about tag-based scripting, but I'll be damned if I can find one.