If you have done well optimizing for google yahoo will serve you well too though keyword density seems to play more of a factor allong with internal linking.
Hey i dint know that backlinks were not important in yahoo....page seo be done with informative and key word rich content...any other ideas??
The great thing is that you can improve your ranking in Google and yahoo simply by getting more contextual links. The great way to get these kind of links by writing and distributing articles.