1. Put your server into maintenance mode.
2. Enable SSH on ESXI.
3. Open firewall for outgoing http requests.
esxcli network firewall ruleset set -e true -r httpClient
4. Find a list of all of the available updates.
esxcli software sources profile list -d https://hostupdate.vmware.com/software/VUM/PRODUCTION/main/vmw-depot-index.xml
5. Filter them to this year and for version 5.5.0
esxcli software sources profile list -d https://hostupdate.vmware.com/software/VUM/PRODUCTION/main/vmw-depot-index.xml | grep "ESXi 5.5.0-2014" | grep "standard"
6. Dry Run.
esxcli software profile update -d https://hostupdate.vmware.com/software/VUM/PRODUCTION/main/vmw-depot-index.xml -p ESXi-5.5.0-20141204001-standard --dry-run
7. Install.
esxcli software profile update -d https://hostupdate.vmware.com/software/VUM/PRODUCTION/main/vmw-depot-index.xml -p ESXi-5.5.0-20141204001-standard
8. Reboot.
reboot