Wait, are we talking about the same "resources"? I thought of resources as you have Food, Production and Commerce. Now, you can add "Corpses". Only now I realize that those are "Yields", not resources. My bad
If you mean resources as in Bonuses, then yes, you have the same problem as with the features. You'll also have the same problem with improvements too.
I was thinking along the lines of making each corpse add to a Yield value, so you can look at the field and see your Food, Hammers, Commerce and Gravestones or something. It would be easier to implement graphically (I'm assuming, since I've never really done it but I know that you can have more than one yield value per square so I see no reason why not). The problem I see with this is that a user can't see corpses unless they turn on their yields for the whole map, which might get kind of annoying.
@ Civmansam:
Well, that won't work, since in Civ4 there are no such things as "Resources". I think Duke was talking about Bonuses, and I was talking about Yields.
Try to do it just with the setFeature like I had and see if you can get it to work that way, just to make sure that we can fill in the "setFeature" with whatever we want to later.