Run into the room, pressing pause immediately when entering. Jump into a mid-air spring ball jump to reach the ledge above. Perform the spring ball jump while still moving forward, in order to get a boost in jump height.

Entrance condition:

{
  "comeInRunning": {
    "speedBooster": true,
    "minTiles": 5.4375
  }
}

Requires:

"HiJump"
"canTrickyJump"
"canLateralMidAirMorph"
"canTrickySpringBallJump"
{
  "or": [
    "canSpringFling",
    "canInsaneJump",
    "can4HighMidAirMorph"
  ]
}

Dev note: This assumes extra run speed of $1.B entering the room, at least $2.6 when jumping (a 2-frame window in the worst case).