While on the elevator platform, place a Power Bomb midair, pixel perfectly, at the height where Samus can crystal flash while standing.
The Power Bomb will need to be centered on her hitbox, which may not be possible with a full height jump.
While standing, press the crystal flash inputs, where the down press is not pressed until the last frame, where the inputs are checked.
This occurs approximately 13 frames after the Power Bomb explosion is completely gone.
Instead of crystal flashing, Samus will go down the elevator. If it was done properly, Samus' beam will be grey in color.
See also: Tech Page