Forget that link. AMXX dont work with the open beta.
-Make a server
-Open the console
-Type in "sv_cheats 1" then press enter
-Into the console type "restart" then press enter
-When back into the server and you have your character selected open the console
-Type in "powerlevel X" where X is the number you want to set as your power level.
So powerlevel 1000000 would give your character a powerlevel of exactly 1 million.
Oh do note that this is a debug command. And as such only works with the open beta. It does not work with any final release.