CUPS-configuration for network-printer

[dac9]

Hi guys

I'm trying to configure my network-printer with "config.scm" as follow:

  (services

    (append

      (list

        (service cups-service-type

          (cups-configuration

            (web-interface? #t)

            (browsing? #f)

            (default-paper-size "A4")

            (default-language "en")

            (listen '("127.0.0.1:631"))

            (preserve-job-files #f)

            (extensions

              (list

                 cups-filters

                 hplip-minimal

              )

            )

          )

        )

My problem is: I don't know how to set the hpp-file and the 
printer-address (192.168.50.2:9100).

Thanks in advance

dac