This is a very complicated process. I'll list the steps here.
1) Get on game 2) Spin around 3 times 3) Enter up, up, down, down, left, right, left, right, b, a, start. 4) Max at least 3 pirates (maxing more can increase your chances). 5) Defeat every boss in the game 1,000 times. 6) Defeat Kane 1,000 EXTRA times. 7) Defeat the Smuggler's Arena 100 times. 8) Repeat all the steps again (the order must be the same, or you may mess up the process) 9) Enter the Smuggler's Arena again and enter up, up, down, down, left, right, left, right, b, a, start to unlock the secret final battle. 10) Defeat Fin Dorsal, the Valvida Brothers, the Duck of Death, General Tso, Rooke, the Hydra, and Kane all in one epic battle to the death. The chest dropped at the end has a 1% chance to drop admin perms, so good luck!
Or alternatively, admin powers can only be used by staff of the KI team and cannot be obtained by players. The above instructions may or may not be an elaborate ruse that doesn't actually work, but it's worth a shot!
(Really though the only way to gain admin powers is to be Kingsisle staff, I just wanted to have a little fun with this)