Theme uses {!$post->excerpt} — plugin doesn't work

Hey There

This plugin is exactly what I need, but instead of using “the_excerpt()” to display excerpts, the theme I’m using uses “{!$post->content}.” The developer suggested I change it to “{!$post->excerpt}” which gets the excerpts to display, but I need your plugin to control additional settings.

Any advice?

http://wordpress.org/extend/plugins/advanced-excerpt/