Well unfortunately there are no overlays that you can turn on for 4:3 safety within the camera. There's also no Magic Lantern support for the camera so that's not an option. One method would be to use an external lcd monitor that has the overlay if you can get your hands on one before the shoot ( I recommend SmallHD DP6 rogar-BigGrin(DBG)) Of course the old standby is to use tape to mask off the area of the camera's lcd that is outside the 4:3.
ok, I just noticed I do have this on "safety line" on my HMC40. Im assuming I would have to just stay in the safety zone and when I render it out of Sony Vegas I would have to crop it?