How Configure SAP server to use the new "virtual" hostname

We have an Application server installed on a physical host. We want to move the same to a virtual hostname.

Note 962955 - Use of virtual TCP/IP host names

The above note talks about
4. Next, install or configure your SAP server using the new "virtual" network identity. Information is available in the installation guides at http://service.sap.com/instguides.

However i don't find much of information available other than for install. How to configure the instance to virtual if it is already installed ?.

We tried creating new start and instance profile with the names of virtual host and also updated the parameter SAPLOCALHOST = <virtual host name> in both.

However the startsap command does not identify the new start profile, so it starts with the old profiles and hence on the physical host name.

How to make startsap to identify the new sap pfrofiles of virtual hosts?

Thanks,

dev