Domain registration is available directly through Typepad. By registering through Typepad, the mapping of your custom domain will be seamless, and you won't need to make any changes to the domain as Typepad will take care of the mapping process for you.
If you already a registered domain or prefer to use a third-party registrar, please check to make sure your registrar (the company where you register your domain name) supports "custom DNS services" and allows you to edit the CNAME Record for the domain. Registering a domain with Typepad ensures your domain supports custom DNS, and the mapping setup is done within your Typepad account.
If you're not sure if your third-party registrar supports custom DNS services, here is a suggested message that you can send to them via email or their customer support area:
I'm using Typepad (http://www.typepad.com/) to host my blog. Typepad supports a feature called domain mapping, where my domain can be pointed at their servers. In order to use this feature, my registrar must support custom DNS services. I need control over the DNS records that describe my domain, and I must have the ability to create and modify A and CNAME records. Do you offer such a service? Please send me more details on how it works and how I can turn it on for my account.