Jump into the second ceiling Samus Eater in Hellway. After teleporting and passing through the transition, X-Ray climb to reach the space above, to the right of the morph tunnel. Samus will be off-camera, so it may not be easy to tell when the climb is done.

Entrance condition:

{
  "comeInWithSamusEaterTeleport": {
    "floorPositions": [],
    "ceilingPositions": [
      [
        10,
        3
      ]
    ]
  }
}

Requires:

"h_heatProof"
"canXRayClimb"
"canOffScreenMovement"