Yes you can.. go into the Clock settings.. I believe they're under Display Maintenance (but I am not sure now without looking at the documents) and just set the time zone offset to 0... it won't mess up other units.. At least, it worked in my 2-screen setup
It will have a little "z" next to it... I had it set up that way on my plane.. one was showing local (with "L" next to it) and the other was Zulu with little "z" next to it..