Entry location: Norfair
It's very tricky to do, but you can use the Speed Booster to get Screw Attack before defeating Ridley!
First head to the room directly below the path to Screw Attack (It's directly to the left of a save room). Locate the hidden Speed Booster blocks on the ceiling (using bombs) and remember where they are. Head one door left and position yourself as far left as you can. Make sure there are no enemies in your way, shoot open the door, aim diagonally down, equip missiles, then start running to the right. Immediately after entering the next room, you must missile the enemy on the ground while still running, then quickly shoot open the next door. Once you're in the Save Room, you should reach full speed, so crouch to store energy, then press A, then left, to dash against the hill (keep holding left to keep Samus running). Still Speed Boosting shoot the door and run into the room on the left. Crouch to store energy again, then position yourself directly below the Speed Booster blocks you located earlier. Press A, then up, to jump through the ceiling. Head 2 doors right and pick up the Screw Attack!