From: 	Rickard Osser

1,      The directive "AuthAuthoritative on" which is in the readme 
        file is not correct, it's not used in Apache 2.2 at all.
2,      The dirctive "AuthBasicProvider external" need to be in 
        the .htaccess file, otherwise it doesn't work.
3,      For authenticating a user the following works:

AuthType Basic
Authname "Don't go here if!!!"
AuthBasicProvider external
AuthExternal pwauth
Require valid-user

4,      For authenticating users in a group/site the following works:

AuthType Basic
Authname "Don't go here if!!!"
AuthBasicProvider external
AuthExternal pwauth
GroupExternal unixgroup
Require group site10

        Remember to remove "Require valid-user" if you want group 
        auth...