When you get that 403 error, check your error logfile - does your IP address show as 127 or localhost? If it doesn't, then you'll need to add that IP into your "Allow" line. You can only have one IP, IP range, or hostname per "Allow" line.
Finally, authentication will NOT work unless you've told Apache to allow authetication under the Sites directory. This involves opening your username.conf file (located in /etc/httpd/users/username.conf) and adding "AllowOverride AuthConfig" (for just authentication control) or "AllowOverride All" (to allow overriding of all default Apache directives).