LIT + Casein + authlogic

I'm trying to integrate LIT http://ift.tt/1Fzw2Vq in a casein CMS install http://ift.tt/WlceWt

Casein uses authlogic for user authentication, to use the same sessions, casein can be configured to use the app's authentication function. It gives the example ":authenticate_user! "

# in config/lit.rb
# Which authentication function to use (ie. :authenticate_user!)? When set to
# `nil` will let everyone in.
Lit.authentication_function = :authenticate_user!

It seems like I should be familiar with this authentication function's name, I tried to search the casein and authlogic source without luck.

Thanks for your help