Okey, so fallout is out and right now there is 34 downloadable (mods) on Nexusmod already.

So I'm wondering, when will I be able to but mods on my Xbox version and how do I use them?

First step is to wait a few months until Bethesda announce how it's going to work.

damn... guess that won't be a problem anyway, got the whole game in front of me, unexplored

It won't be before 2016 anyway. Probably March or something. But atleast the Xbox One and eventually PS4 will get mods and that is a good thing.