Actually google and Go Daddy have the instructions for what you need to do :

http://www.google.com/support/a/bin/answer.py?answer=47610
and
http://help.godaddy.com/article/680#cnames


Just ensure that the host(subdomain for the alias name) is www. which points to ghs.google.com if you intend to  your domain name to be mapped to your google apps site.

Regards