Yes, I had one Unity server reporting to a domain Insight Manager server prior to moving to Cisco's Operations Manager application. You will have to work with your Insight Manager support person to configure the snmp service properties - Security tab for the Community string. I would also recommend checking the radial button "Accept SNMP packets from these hosts" and add your CIMXE server. The support person will point the CIMXE server to your Unity server's IP address and the agents will be installed. This is supported software on the Unity server - http://www.cisco.com/en/US/docs/voice_ip_comm/unity/5x/support/5xcusupp.html#wp466823
You might want to check out the remote serviceability kit as well (http://www.ciscounitytools.com/App_RSK.htm). This apparently adds SNMP/SYSLOG functionality to Unity, so you may be able to get Unity alerts directly in HP SIM.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.