I'm not sure about inventory at the right hand side of the story view screen, but I know you can put links there that act like an item, here. About 4-5 clinks before you see it done though, and I would suggest viewing it on Alex so you can see an extensive example of it. (WIP)
Of course, that uses a whole bunch of scripting, html mainly I think. Not entirely sure, but it's a type of script not designated just for this site, but can be used anywhere. Like making a background (the version depicted in the article that was just for this site doesn't work anymore).
If you want to know how it's done, you'll have to ask quiller if he ever pops up again. He hasn't been back for over a month, though he's been away longer and then come back.