Take a look at the official RPG Mod thread;
http://forum.thegamecreators.com/?m=forum_view&t=184278&b=21
RPG Mod was created so that you can make adventure games, it includes inventories, so could be just what you're looking for if you don't mind installing a mod.
All the files you need are in the 1st post in that thread, there is also a number of tutorials included in the manual, which can also be downloaded in the 1st post.
I'm sure Flatlander and Ched80 would be more than happy to answer any questions you might have about RPG Mod.
Hope this helps