Where can I locate the visual trigger setup on the 5 or 6 series MSO?

The visual trigger option is not listed in the trigger type selection initially.  To setup the visual trigger, simply click on the "DRAW A BOX" icon (located in the lower right corner of the display) to draw the areas for the visual trigger.  After the visual trigger areas are defined, the visual trigger tab would be included in the trigger menu for setup.

The visual trigger is available with firmware v1.8 or above on the 5 series MSO.  It is available on the 6 series MSO with its initial firmware.