The website only mentions the easing option:
# easing: Name of the easing equation.
But there's no example.
How to use this feature?
The examples are here: http://demos.flesler.com/jquery/scrollTo/
Use like so:
$.scrollTo( '#options-examples', 800, {easing:'easeOutQuad'} );
These easing functions don't come built in though. You can use the jQuery Easing plugin. This then supplies the following easing functions: