Use GUI checkbox for scripting

Hi There

How can I use the GUI checkbox option in my script to turn Motion Blur ON or leave it OFF?

For example I´ve generated this checkbox in my GUI Panel:

var checkMB = groupTwo.add("checkbox", undefined, "Motion Blur ON");

How can I ask if it is checked or not and use this information.

For this example I want to ask "if I plan to use Motion Blur". And if so, the Motion Blur Button in the Timeline should set to ON.

I found some code for the Shy Button, but nothing for the MB button. (xxx.hideShyLayers = true;)