How to configure DNS for new domains automatically in WHMCS?

I've got WHMCS set up to allow customers to register domains, buy standard cpanel hosting, and buy WPMU hosting.

Where cpanel has its own DNS server and the registered domain gets set to the cpanel server as its DNS is ready to go there, how can I add A records to point new domains to the WPMU hosting?

I'm imaging some sort of default template for DNS with the registrar but I can't find any way of doing that unless I'm missing something. I'm using ResellerClub.

How are people doing this to get fully automated WordPress hosting on new domains?