That would depend which MG it is. Modern (approx. post 2000) MGs are based upon Rovers but given different names and turned sportier. For example the Rover 25 was converted into the MGZR which has then been used in races and is more appealing to younger people
To install a new window regulator on a MGRZ driver's door, remove the door panel and the wiring attached to the power window mechanism. Remove stereo speaker from the inside door and the window glass. Remove the old window regulator and replace with new.