First you have to get a local copy of the epsos-common-components openncp-portal repository with this command:
git clone https://[username]@code.google.com/p/epsos-common-components.openncp-portal/
and then inside this directory you have to run the following commands:
mvn package
mvn liferay:deploy
Double check that before running mvn liferay:deploy you have configured pom.xml to point to your LIFERAY_HOME
<liferay.auto.deploy.dir>/home/karkaletsis/Documents/j2ee/liferay-portal-6.1.0-ce-ga1/deploy</liferay.auto.deploy.dir>
in order to correct deploy the epsos portlet to your liferay binary installation directory