I never got to try the Screen Warp glitch (I only have the DX version), but I do know of another glitch that works in both versions: the Glitch World!
First, go and kill some enemies (different amounts produce different glitch worlds, killing no enemies lands you in Goponga Swamp), then go to Madam MeowMeow's house and wedge yourself in the top-right area of the house, where the house meets Bow Wow's (I think that's her name) kennel. Push yourself up against the wall and gradually inch to the right, until you appear stuck in the right wall. After that, just keep going down (whilst remaining stuck in the wall) until you enter the door. You'll get some weird as places.
Of course, another fun (and easier, providing you have the right items) thing to do is go and burn chickens.
