Custom Name Servers can be setup by registering the following name servers IPs through your domain registrar:

ns1 - 208.68.171.66
ns2 - 208.68.171.76
ns3 - 208.68.171.67

Once registered it is necessary to set up a Name Server Mask. This can be done through the Control Panel.  From the Control Panel to Account Settings, and to Global Settings. Setting a custom name for your servers can be done within the text box next to the "Name Server Mask" label. The other option in Global Settings allow you to more specifically tailor your server for your needs.  The ns IP's (ns1, ns2, and ns3) also need to be setup as DNS Records.  Follow the link path from your Control Panel, to Domains, and to DNS Zone Editor.  The ns records should match respectively to the ns# IP's.  The ns records should be in the record name, and the IP should be the record data.