Mapping seo and other questions

Hi, I need to map about 50 domains to one WPMU Subdomain installation.
Eg.
abc.com mapped to abc.example.com
xyz.com mapped to xyz.example.com and so on

My criteria:
1. Google will not see both abc.com and abc.example.com as duplicate contents(hide abc.example.com from google).
2. Users will still see abc.com in the browser address bar

Which is the best way to map and redirect those domain names?
If I use "Addon Domain" in Cpanel to achieve this, do I still need to "Add the CNAME pointing to this url" and "add A Record pointing to the IP address of this server"?

Thanks very much in advance.