Replying to 2.35.1 Aspect Ration Crop Help

I would like to try and film some videos at the 2.35.1 aspect ratio. I have seen a lot of kids that use the 2.35.1 but dont film for it which results in cropping heads and feet, which i dont want to do. I want to draw the crop lines on my plastic screen protector so that i have it for a reference when i shoot. Any idea on how to figure out where to draw the lines? I shoot on a t2i which has the 3 inch LCD screen. Thanks!