On Slack 13.1 with OpenVAS 3.1 Source packages
Download all from slackbuilds.org and install openvas-libraries, openvas-scanner, openvas-client in this sequence.
Note that as of 2011-02-16 slackbuilds.org offers openvas-client-3.0.2 wheras the openvas download page offers openvas-client-3.0.3 for the 3.1 main version. Take the newer version and ajust the openvas-client-SlackBuild file accordingly.
The installation creates /etc/openvas/ and 2 files in /etc/rc.d/. You might copy them to a save place for reference.
Create server certificate as root: openvas-mkcert -q. This also creates openvassd.conf and openvassd.rules in /etc/openvas
Add an openvas user as root: openvas-adduser and restrict scans to your subnet to avoid (accidental) scans outside, eg:
accept 192.168.0.0/24 defautl deny
Update plugins (= NVT's = Network Vulnerability Tests) from Internet with openvas-nvt-sync as root.
Openvas??? starts the client. You must explicitely connect to the server by pressing the connect-button.