is it possible to install HUM+CS and CSM in the same server?
Yes, if CSM's CS is the same version as that of HUM's. For example, in order to maintain Cisco support:
"We do not support installation or coexistence on one server of Security Manager 3.3 and any release of Common Services earlier than 3.2. Nor do we support coexistence with any third-party software or other Cisco software, unless we state explicitly otherwise in this guide or at http://www.cisco.com/go/csmanager. "