I have read documentation for customized skinning in Jboss Portal and could not find the exact steps that needs to be followed in getting this resolved.
1. Create a new skin ( called MySkin) in gatein.ear\01eXoResources.war\skin. For now, I just copied the DefaultSkin directory and renamed it to Myskin and also copied the StyleSheet.css into MySkinStyleSheet.css
2. Added the following to the the gatein-resources.xml (gatein.ear\01eXoResources.war\WEB-INF\gatein-resources.xml)