It's pretty straightforward to setup debugging for the GWT project from Eclipse. Here are the steps below:

Install Instructions

1. Install the Eclipse GWT plugin using the appropriate update site URL:

Eclipse 3.5 (Galileo)
http://dl.google.com/eclipse/plugin/3.5
Detailed instructions for Eclipse 3.5 http://code.google.com/eclipse/docs/install-eclipse-3.5.html

Eclipse 3.4 (Ganymede)

http://dl.google.com/eclipse/plugin/3.4
Detailed instructions for Eclipse 3.4 http://code.google.com/eclipse/docs/install-eclipse-3.4.html

Eclipse 3.3 (Europa)

http://dl.google.com/eclipse/plugin/3.3
Detailed instructions for Eclipse 3.3 http://code.google.com/eclipse/docs/install-eclipse-3.3.html

2. Once you have installed the plugin and restarted Eclipse, go to:

Run >> Debug Configurations

Right click on Web Application and select New to create a new Web Application Debug Configuration

3. Within this new configuration, set the "Project" as sipXconfig-gwt

4. Click on the "GWT" tab and set the browser "URL" as UserPhonebookSearch.html

Notes

More info on the Eclipse GWT Plugin http://code.google.com/eclipse/docs/users_guide.html

In order to output human readable Javascript, when compiling the GWT project, Inherit the debug GWT package SmartGwtDebug instead of SmartGwt in user_phonebook_search.gwt.xml.

If you need access to the SmartClient Developer Console, inherit SmartGwtTools in user_phonebook_search.gwt.xml. More info on this can be found here http://forums.smartclient.com/showthread.php?t=3033