Back in January I reported a bug/missing feature the Glassfish server adapter for Eclipse. The asadmin tool allows you to easily create domains for the server. In a typical setup I separate the domain dir (configuration) from the glassfish installation directory.
While the plugin allows you to set the used domain it is not possible to select the directory where the domain is installed. It expects the domain in the usual subdirectory of the Glassfish/SJSAS installation.
Looks like work Rochelle Raccah from Sun now started working on it today.