Do the following:
1. Open the Download Updates window from the Patch and Compliance tool.
2. In the Definition Types section, select "LANDESK Antivirus Updates" under Security | Antivirus.
3. Click the Schedule Download button at the bottom the window to create the task.
If you do not see the LANDESK Antivirus Updates option then you have a licensing problem and will need to contact LANDESK Support to get it fixed.