With the release of ITMS 8.0, a new core setting has been added: "TaskServiceAdvancedSettingsAllowed".
  <!-- TM Enables/disables to edit Task Service advanced settings over the NS Console -->
  <customSetting key="TaskServiceAdvancedSettingsAllowed" type="local" value="False" />

With this new "TaskServiceAdvancedSettingsAllowed" setting (under c:\programdata\symantec\smp\settings\coresettings.config) you need to change it from "False" to "True" so you can see and edit Task Service Advanced Settings over the SMP Console.

To change the above setting, navigate in the console to Settings > Notification Server > Core Settings and search for "TaskServiceAdvancedSettingsAllowed"

You can also use "NS configurator" located here (default location): C:\Program Files\Altiris\Notification Server\Bin\Tools\NSConfigurator.exe

Go to SMP Console -> Settings -> All Settings -> Settings -> Notification Server -> Site Server Settings -> Task Service -> Settings -> Task Service Settings.

This is what "Task Service Settings" looks like before enabling the "TaskServiceAdvancedSettingsAllowed" setting:

Note: with the ITMS 8.5 and later releases, "preferred hostname" uses a communication profile:

Enabling the "TaskServiceAdvancedSettingsAllowed" setting will give you this: