First off, are we tagging them even if they are indexed? (which as far as I know) a lot of the tutorial forums are.
EDIT: I think the tags are here to help non-members to find things via site searches and stuff, in which case the threads would need to be tagged - or we could go down the route of just tagging the index threads to link people to them where they can find what they want.
If we are, how do we want to do it? There have been a few suggestions thrown around here and there, and I think the main idea is something like this:
[GAME tutorial] ; [MODDING AREA]
Does it need to go more specific than that though? I'm not a modder so I don't really know how niche things can get, so like if there was a tutorial on "modding m2tw horse to look different" could that be covered sufficiently with just [m2tw tutorial] ; [unit modelling]?