It can help to moonwalk towards a Mella that has never been on screen, so that it starts swooping immediately as it first enters the screen. This will make it so that when Samus is below it, it will always swoop and go up slightly compared to the previous swoop. Once it is close to the right height, move away so it stops swooping, freeze it and quickly try the clip, if it doesn't work, quickly leave and try again.

Entrance condition:

{
  "comeInWithGMode": {
    "mode": "indirect",
    "morphed": false
  },
  "comesThroughToilet": "any"
}

Requires:

"canComplexGMode"
"canManipulateMellas"
{
  "or": [
    "h_preciseIceClip",
    "h_highPixelIceClip"
  ]
}
"canInsaneJump"
{
  "or": [
    "Morph",
    "canTrickyGMode",
    {
      "enemyDamage": {
        "enemy": "Mella",
        "type": "contact",
        "hits": 1
      }
    }
  ]
}

Exit condition:

{
  "leaveWithGMode": {
    "morphed": false
  }
}

Bypasses door shell: true

Dev note: This is only for indirect G-Mode, because it is trivial while in direct, and would use a different strat.