You can start by writing a letter (yes, a hand written letter. This shows a greater interest since you've taken the time to do so) to MGM and let 'em know you want this horror/comedy classic on DVD. Here is their address;
You can call MGM's customer service line at: 1-877-646-4968
Click here and select "MGM DVD" from the drop down box, from there type your e-mail address (that let's them know you're a real person), and type your request for "Return of the Living Dead" on DVD.
There is also an on-line petition that you can sign! Go here to add your name to the list!
Tell MGM you'd LOVE to see a "director's cut" of "The Return of the Living Dead" released on DVD!