WebSVN and SSPI authentication

I’ve set up two repositories on a domain and I want to use a WebSVN installation to view them. The users are different for the two repos, so I’d like to setup a per repository authentication in WebSVN. I’ve tried to follow the instructions in the installa file (modify .htaccess and adding the two repos in config.php) but I get an Error 500 on the server if I try to open a page.

Did anyone reach to use this authentication method with WebSVN here on DreamHost?