Opening the Safe
Unlock the safe using the code "1873." The safe is in the "Panic in the Brotherhead" location in the room you enter from the window. You can also read the code off the desk if you examine the desk with Mei.
Delta Beta Frat House Code
Use the code "Picasso" at the top of the stairs in the Delta Beta Frat House to unlock the door. This is at the location "Outside the Brotherhood."
Delta Theta Gamma Party Code
Enter the code "Mozart" into the first door you discover while playing as Mei (it's in front of the Brotherhood.) Mei can also search with the encryption device to uncover the code.
Open the Door to Get to Jun
Use the code "Freud" on the keypad in the main lobby of the girl's dorm. This will be at the second door you see.
Hack the Computer to Get Dynamite Ingredients
Enter the code "Einstein" on the computer in the Security Room. It is vital that you keep the soda that you got earlier from the basement of the hospital; this is the last ingredient of the dynamite.
Easy Lockpicking
While using the final rod in the lockpicking process, make sure the pin is stuck. Before it gets unstuck, shake the Wii remote quickly up and down. If done correctly the pin will go through the rod and into the hole at the end.
Opening the Door at the End of the Game
After defeating the game, wait until the end of the credits. You will then be shown a clip, after which you should run to the house to get away from the monsters. This will be the area where you first saw the professor. Find the dead body and get the flare, bat and medallion from the body. Put both medallions on the door and connect the lines to each other.