Good moderators don't need to be necessarely profilic posters, so what about:

- 1 year around, to proof that you have a good perspective.

- 250 posts, enough to tell that you know how a poster feels like.

- 100 Thanks received, so you somehow proof that you have support from a bunch of readers.

- A plan. Why do you want to become a moderator.

- Visible activity and experience in the area or task you want moderate.

For instance, TrueJournals would look like fitting in this profile.