Since the domain has been transferred to DreamHost now, you can do it through our panel under the Domain Registrations tab:
[*] Click the domain name in the list.
[*] Click the "Modify WHOIS info" button at the bottom of the WHOIS information.
[*] In the dropdown menu at the top of the page, select "Nameserver" (last item in the list).
[*] Switch the radio buttons to "Use DreamHost's nameservers" and click "Update".