Is it possible to create a spell that has a duration based on game time? What I mean by this is, can I create a spell that lasts for say, 3 days, but have those days be based on the actual game days rather than real world days?

I know that this can be accomplished with scripts very easily, and I've done so before. But if possible, I'd like to create a spell that has an actual duration in the magic buffs menu, and shows how long the spell has remaining there. As far as I'm aware, if I use scripts to control the duration, this is not possible.

Anyone have any ideas?