Here's the deal.
The staff decides who they want to help out with modding. If we think you're what
we're looking for when
we're looking, we'll give you a tap on the shoulder and pull you aside. In all cases, you're part of the community.
So in other words, there isn't really a "way" to become a moderator.
If you're posting here, hopefully it's for your love of the game and the community - not to become a mod.