Did you check out the VCS admin and deployment guides?
http://www.cisco.com/en/US/products/ps11337/prod_maintenance_guides_list.html
http://www.cisco.com/en/US/products/ps11337/products_installation_and_configuration_guides_list.html
Like the X7.2 admin guide:
http://www.cisco.com/en/US/docs/telepresence/infrastructure/vcs/admin_guide/Cisco_VCS_Administrator_Guide_X7-2.pdf
and the basic vcs-c/e deployment guide:
http://www.cisco.com/en/US/docs/telepresence/infrastructure/vcs/config_guide/Cisco_VCS_Basic_Configuration_Control_with_Expressway_Deployment_Guide_X7-2.pdf
could be a good start for basic understanding.
Is this for some intra company setup or some external call flow?
In general for business to business setup I would prefer routing via the DNS zone, so a neighboring to a specific
external VCS is not necessary.
Why dont you start talking to the remote site which you should neighbor up with to give you some more information
why and how. If you trust them and they are knowledgable that might be the easiest way to go :-)