User Login

I need to create a couple new variables on the login page for use in a custom application.

I have added a couple fields to the author table, I need to store the values of those fields when the user logs in into a session variable or whatever.  There are three pages reguarding login, which page or pages do I need to add too and what specific code?

Reason I ask is hopefully someone can help me out licky-tity-split ...! :P