[news.eclipse.tools] How do I register my builder with a project?

[steven_squire@xxxxxxxxxxxxxxxxxx (Steven Squire)]

I've created a new subclass of IncrementalProjectBuilder and added the
appropriate tags to my plugin.xml file, but it's unclear to me how to
register this builder with my project. Does a new implementor of IProject
have to be created or can new builders be registered with existing
projects?

Thanks,
-steve