Below mentioned is the procedure to register private nameservers at DirectI - Channel domain name registrar :
1) Login to your Control Panel, search for the domain name and proceed to the Order Information view.
2) Click the Child Name Servers link.
Add a Child Name servers:
Enter the hostname of the Child Name Server you wish to add in the Add New Child Name Server box, key in its IP address and proceed. Each Domain Name can have up to 13 Child Name Servers associated with it.
e.g : ns1.domainname.com
Modifying / Delete a Child Name Server
-Modifying Hostname - Make the modifications in the hostname text box and click on Modify Hostname
-Modifying IP Address - Make the modifications in the IP Address text box and click on Modify IP Address
-Deleting a Child Name Server - Click on the Delete a Child Name Server [Red Cross] button
Apart from the steps above, one will obviously need to configure your DNS Servers and bind the required IP Addresses to them. Additionally, in your DNS Record for the zone domain name one will have to add the required 'A' records or 'CNAME' record for the above Child Name Servers.
It will take approximately 12 hours to propagate.