You can script equipping an item with:
/inventory equip [Item No: 0-256] [Slot: 1-20] [??]
Unfortunately finding the item number is very difficult and I have only been able to find brute force techniques, i.e.
/info inventory [Item No: 0-256]
The items in your inventory [including House Vault and Bank - you will get a lot of "You are currently not in a Bank transaction"] use this range. Items equiped do not have an inventory number.
The Slot number is where you want to equip the item, some items can be equipped in multiple locations, example include 18 first activatable slot, 1 secondary weapon etc. And is an optional argument.
No idea what the 3rd argument is for.
And here's the really big problem, when you unequip an item you are not guaranteed to get the same item slot in your inventory, i.e. you have to find the item number again - making this useless information
Regards
-A.