Pretty sure it's possible, but why? If you're just building, you can spawn an item. If you're fighting, that's a bit cheap to have access to every one of your weps and other people not knowing which ones you have. Possible, but not useful.
There's an addon that does this with your default items. I'm not entirely sure that what you're suggesting can be made, though.
What is it called?
http://forum.blockland.us/index.php?topic=108211.0
Can you get the guy to read this topic??
Tez the Twat is perma'd
Feel free to PM him...
Did no response