This can be done but not using the configuration web pages. To do this, you need to either:
1. Use JNDI connections to Director and Results, configured on the app server. See the help topic here: http://www.oracle.com/webfolder/technetwork/data-quality/edqhelp/Content/administration/change_database_configuration.htm
2. Edit the director.properties file manually to specify the connection strings directly.