SLES8 installation from authenticating HTTP

Hello, I'd like to install SLES8 via HTTP, and use authentication. It works fine with YOU, but SLES seems to be unable to install via auth. http. "401 Authorization required" is all I get, is there a way to set username and password? I also tried install=http://username:password@<ip-addr>/sles8 at the install prompt, but this fails, too. Thanks in advance, Johannes Klug