NOTE:  The only thing different for the PC version of MKT is the Chameleon code.  To do the Chameleon code:
At the character select screen, choose any male ninja.  Right after selecting a ninja, hold HP+LP.  Hold these buttons until the fight starts.  When Shao Kahn says "Fight!" the ninja will explode into Chameleon.

You can also exit a match in the PC version by hitting Start, then Select in the match.