To transfer a domain name to Intermedia Name Servers, the owner of the domain needs to contact the domain name Registrar (from which the domain was purchased ) with the request to make the transfer. Usually you should be able to update the record yourself specifying Intermedia Name Servers (read the Knowledge Base article on What is the Intermedia Name Servers (DNS) information? for more information). If you do not know how to change the records, please contact the Registrar directly for instructions.

The largest domain name Registrars are:

To find  the Registrar of a domain name, you can go to the InterNIC site. You will need to type in the domain name, select Domain and click Submit.

After you make the change, the information usually gets updated with Registrars’ Databases within 12-24 hours.

Please be aware that due to the distributed nature of DNS, changes applied at the root of the DNS tree may take up to 2-7 days to propagate across the Internet. This happens because all local (ISP’s) DNS servers cache domain IP addresses for 1-7 days, so that even when a domain is added to the root, it may still not be accessible from different locations on the Internet.

See also:
What is propagation?