Yes that is possible, at the time of signup you need to select the option "I will use My Existing Domain and update My Nameservers only."
DNS information will be sent in the welcome email once you signup.
__________________ WebHosting.UK.com :: Leader in Web Hosting
cPanel Hosting | Windows Hosting | Reseller Hosting | CLOUD HOSTING 100% Uptime Dedicated Servers - Fully Managed UK dedicated servers with 24x7x365 Support Great Opportunity:: Join our Affiliate Program for FREE & earn up to £300 per sale.
Follow Us on Twitter and FaceBook