How to track different button clicks with Google Analytics and AJAX?

Question

I have several pages, let's call them A, B and C.
Each of these pages has a form where the user can type in some information and click a button to send those information to the server. This button click is performed in an UpdatePanel to prevent a full postback.

A customer of ours now wants to know how many % of the using visiting each site (A, B and C have different URLs) use this form. (Meaning I need seperate values for A, B and C)
How to I track this in Google Analytics? It seems that I have to create a conversion(??) for each page. Is that correct?

How must I modify the existing web application to let Google Analytics know, that a user submitted the form. (without the need to redirect thank to xy amount of different thank you pages)

The only piece of information I've found so far is this: http://www.google.com/support/googleanalytics/bin/answer.py?hl=en&answer=55519 Unfortunately, this FAQ entry does not cover my answer.

Answer 1

You need to call pageTracker._trackPageview with a unique string when the button is clicked using Javascript.

For more precise instructions, please provide more detail.

Answer 2

A project i have released allows for easy integration with Google Analytics to fire page views and events through native .net code.

This way you can simply call a method that will log either and event or a page view for you. You can do this in your web service's code.

It's called GaDotNet and can be found here: http://www.diaryofaninja.com/projects/details/ga-dot-net