There's a script that's built into the AMP that does it. In order to upgrade, you'll need to know what version you want to upgrade to (ie 5.3.1), as well as your login and password for AirWave's support site.
To run the script you can just do:
# start_amp_upgrade
And you'll be prompted for the information above.
Occasionally it is necessary to upgrade to an interim version before upgrading to the latest or other desired version. As a general rule you should not upgrade more than two sub-versions at a time. Example: if you currently have v6.0.4 and you want to upgrade to v6.4.1, you would need to upgrade to, say, v6.2.3 first, then upgrade to v6.4.1. For more information on how to do this, please refer to the following Knowledge Base article:
Multi-step upgrade via interim version
https://arubanetworkskb.secure.force.com/pkb/articles/FAQ/Multi-step-incremental-upgrade-via-interim-version
You may also need to upgrade the Operating System if your server is running on CentOS 4. Please refer to the following Knowledge Base article for more information:
Upgrading from CentOS 4 to CentOS 5.