Install the appropiate Pointed patch available for the current ACS version.
For 5.3 --> Pointed-PreUpgrade-CSCum04132-5-3-0-40.tar.gpg
For 5.4 --> Pointed-PreUpgrade-CSCum04132-5-4-0-46-0a.tar.gpg
Install the 5.5 upgrade package: ACS_188.8.131.52.tar.gz
Install the cumulative 5.5 patch: 5-5-0-46-1.tar.gpg
To upgrade from ACS 5.4 to 5.5 patch-1, it is important to run the command "database-compress" prior to installing the Pointed Patch.
Note: In case of a Distributed deployment scenario, please deregister the secondary from the primary before the upgrade. Once both appliances run 5.5, including the cumulatve patch, register the secondary again.