Domain pointers may be ordered at the time of signing up or through your support representitive at a later time.
A domain pointer is a second domain that points to the exact same site as your original domain.
It cannot point to a subdirectory within your domain or to a different home or index page.
If you require a second domain to point to a different home or index page then you need to sign up for a second account.
Domain pointers are very useful if you own for example yourname.com and yourname.net. They are also very useful if you are simply parking a second domain you own.
Once you have signed up for a domain pointer you must change the name servers associated with your domain. See http://www.batchelors.net/hosting/support/transfer.html.