Start with watching the Alfresco hosted webinar: High Availability Clustering with Alfresco to get a high level overview.
Finally, put it into practice with a working example by following Jeff Potts’s walk-thru of a simple set up to get a feel for it: Alfresco 3.1 clustering easier with JGroups.
AlfrescoWiki: Configuring JGroups and Alfresco Clusters
AlfrescoWiki: Cluster Configuration V2.1.3 and Later
Alfresco Webinar: High Scalability with Alfresco WCM (great information about various options)
Special thanks to Jeff Potts who answered a related query of mine on Twitter.
I’ll be sure to post progress here once I’ve a few working examples.