Just noticed on the Japanese Lexus website that their backup camera with navigation (flip screen) shows a trace/outline of where the car will be if it backs up based on your steering wheel (my wife's Infiniti G35 has this) but it seems that the US version just has the image from the camera with no additional features as the one I am describing? It bothers me that the US version seems to be the crappy version of the CT200h with features only available in other countries, we were even denied the nice blue as an exterior color!
I may be wrong, but I think that requires the parking sensors (you've seen them on bumpers) and the NAV/Backup camera. I know that is an option in non-US markets - maybe someone outside the US can confirm - I know that Lexus offers a front and rear bumper with sensors, so I know that part exist.
Have front and rear sensors on the bumpers and the camera display does have the guide lines. You can also select parallel park assist mode too but not tried this yet. When reversing the lines appear but also the sensors work providing audible and visual warning on the small display on dash and corner of screen.
The UK manual says there is also a display on the rear view mirror but this is not the case, do you have this in US?