Yes in Route Group Configuration adds the IP Address of the gateways, and select the distribution algorithm that you want:
Top Down—If you choose this distribution algorithm, Cisco CallManager distributes a call to idle or available members starting from the first idle or available member of a route group to the last idle or available member.
Circular—If you choose this distribution algorithm, Cisco CallManager distributes a call to idle or available members starting from the (n+1)th member of a route group, where the nth member is the member to which Cisco CallManager most recently extended a call. If the nth member is the last member of a route group, Cisco CallManager distributes a call starting from the top of the route group.
See the Admin Guide of the CUCM, and in your case you can select the Circular Algorithm,
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.