We understand that reading all the docs or setting all the parameters can get tedious, which is why you can get a full Liferay installation working in 2 clicks by clicking on this link: Liferay ClickStart
(Please note that you will need to enter your billing information first, as Liferay requires 512MB of RAM at least, which is not part of our free plans, unfortunately.)
Liferay is one of the most popular Java-based portals in the market. This document outlines the 3 steps required to run Liferay on CloudBees.
Create a new database in your CloudBees account. This database will be populated by the liferway war during deployment. You can create a new database by clicking the "New Database" link on the left handside of the CloudBees console.

You need to bundle jars from the liferay tomcat bundle lib/ext directory into the liferay war file.
The portal-ext.properties file should be updated to have database and lucene related information.
Update the standalone war to include the java libraries and portal-ext.properties

The liferay war is pretty huge and requires quite a bit of memory. Go to your app configuration page and select either medium or large configuration to start your application with. Liferay requires 256M of permgen space, see JVM PermGen Space to setup the permgen space.
Download the CloudBees SDK and deploy the war file. It is a huge war file - so it takes a couple of minutes to deploy. Since the SDK does delta deployments, subsequent redeploys are very fast.
bees app:deploy liferay-portal-6.0.6-20110225.war jvmPermSize=256
At this point you should have a running instance of Liferay on CloudBees.