For some reason I tried doing it but it's not working...
Step 1: Enter your domain into Big Cartel
Go to the Store > Settings > Domains page of the admin area.
In the Custom domain field, enter: (yourdomain).com
Step 2: Add a CNAME with GoDaddy
Log in to your account at [obscured] /default.aspx?prog_id=GoDaddy...
Skills: html, mysql administration, php