yes, but the frame still needs to be fixed to the wall behind the frame (a solid block wall) at the top (not just on the floor) for strength imo. see the picture below for the brackets on the top that go backwards.

going to do it a bit differently now and have the cistern seperate to the toilet holding frame as i want to locate the cistern offset to the side. so now on the look out for seperate frames and concealed cisterns (with air valve remote dual flush)