--Speccy made the entire thing! Thank him for it!
addHook("PlayerThink", function(p)
  -- p is just a shorthand for player in this case.
  -- In fact, player can be replaced with just about anything!

  if not (p.mo and p.mo.valid) then return end
  if not p.mo.health then return end
  if not (p.mo and p.mo.skin == "frontiersclassic") then return end

  -- If we have 100 or more rings, and we hold Custom 1, then apply Speed Sneakers for 2 tics so it's always on if holding Custom 1.
  if p.rings >= 100 and (p.cmd.buttons & BT_CUSTOM1) then
    p.powers[pw_sneakers] = 2
  end
end)