You want to know the procedure or best practice regarding installing Symantec Scan Engine on a clustered environment.
The Scan Engine Server itself does not know that other scan engines exist and is not Cluster Aware. The recommendation for Scan Engine is always a dedicated stand alone server, or a pool of stand-alone servers that can be contacted by an ICAP client. The ICAP client is given a list of available Scan Engines and takes care of load balancing. In the case of a cluster the ICAP client would be given the IP addresses of the individual nodes.This results in the Clustering being redundant feature.