SSO on the same HB machine

Hi, i'm looking for an official guide or tecnical paper, to upgrade vCenter 5.0 to 5.5 and HB from 6.4 to 6.6.  I'll try to explain my configuration:

2 phisical nodes with Heartbeat, vCenter and the SQL db on SAN

i would like to know if there is an official best practice for the installation of SSO on the phisical nodes of  HB. The VMWare guide that i found says:

https://www.vmware.com/pdf/vcenter-server-heartbeat-66-installation-upgrade-windows-2008-2012-physical-guide.pdf

"Before attempting to upgrade from vCenter Server 5.0 or 5.1 to vCenter Server 5.5 you must install vSphere Single Sing-On 5.5 component separately on a different machine (not the primary o the secondary node) and then protect SSO on the separately machine with vCenter Server Heartbeat"

Any suggestions?

Thanks