In order to build ijab you need to do the following steps:
1- Download iJab source code, you can get it from here.
2- Install Eclipse Helios 3.5 or newer (for web development), you can get a copy from here.
3- Install GWT 2.0.2 or newer Plugin for Eclipse, in eclips go to Help-->Install new software , see the below image
Choose Add then enter the link of download (http://dl.google.com/eclipse/plugin/3.6) in case of Helios, then okay
After that eclipse will detect softwares under that link, mark them all and choose next.
Accept the terms and conditions then finish, eclipse will start downloading the required plugins, and ask you to restart the IDE so that changes takes effect.
4-Install GWT-Voices 1.7.0 from here
5-In Eclipse import iJab and xmpp4gwt project.
Choose : File --> import --> General --> Existing projects into workspace
Then browse to the directory where you placed ijab source, and import each as a separate project, ijab_1.0_beta, and xmmp4gwt.
6- Build xmpp4gwt and iJab.
Right click on build.xml and choose Run As->Ant Build on popup menu.
If build successful, it would generate xmpp4gwt.jar into dist/
Rigth click on iJab and choose Properties on popup menu, in
Java Build Path->Libraries, add/modify xmpp4gwt lib path.
Right click on iJab project and choose Google->GWT Compile to
Thats it!! After build successfully you could find the output under war/.