Autorate rule for headsup game to pokertracker?

I am trying to find somekind autorate rate rule for headsup playing.

It would be great if there is any good ones. Even better is someone is willing to share it [img]/images/graemlins/wink.gif[/img].

Maybe I am dumb, but did not find any of those. Have not read any book about that subject either, but if there is some good books, then propably making somekind of autorate rules based to that book might give some direction.