As you can probably tell from my screen name, I graduated from MSU.
Sadly,

my own chapter at MSU is shut right now.
I agree with one poster. Offer to help. Contact the groups' headquarters, or read their websites, and from there, be pointed towards their local alumnae groups, their collegiate chapter's advisers, etc., and offer to help with recruitment, etc. Many chapters have advisers who aren't members of their own groups or any others, they just want to help collegiate-age women. Have a background with bookkeeping, finances, etc ? Offer to help be a finance adviser (oftentimes due to the technical nature of the finances, the FA isn't an alum).
Then, after hanging around a bit, you could seek alumnae initiation.
GO GREEN !!!!! GO GREEK !!!!