You can configure the display name for Unity Connection under Telephony Integrations, Port Group, Contact Line Name.
For Unity 7.0 you can configure this setting for a SIP integration in the UTIM. Go to the integration in question and browse to the SIP Info tab. Enter your diplay name in the Contact Line Name. However....it will not work!!! I have a TAC case that is resulting in a feature request to get this working. Unity sends the information in the SIP packet, but CM is not doing what it needs to do with it, or expecting it in another element or something of that nature. Don't kill yourself on it, though.