Updating an UpdatePanel, calling the server side function from javascript?

I have an UpdatePanel that I want to update when a javascript method runs. I am currently using a workaround where the updatepanel's trigger is a Button, and in the javascript I just call Button.click() and have the server side code tied to the button. I want to eliminate this workaround though. I searched around google and found out how to call static methods with EnablePageMethods, but I need to call a nonstatic method so I can access instance variables of the page.