The Hardware Manager in Vivado 2013.4 provided an option to enter the port number in the GUI when opening a new hardware target.
However, this option is not available in 2014.1.
A Change Request (CR) has been filed to fix this in a future release.
Connection to the cable can be established by entering the following command in the TCL console in 2014.1:
connect_hw_server -host localhost -port 50001 -url localhost:3121
Where 50001 can be changed to an available port for use on the machine.