Warning, Spoiler ahead and if you still want to go by luck, do not continue reading.
According to the source of the cheat is at http://lego.wikia.com/wiki/Minifigure_series_3, there will be "braille" looking mark on the lower end package and here are the cheat sheet taken there.
Since I still have the packet with me, I use to check against and here are the comparison.
and here is the Mummy.
Now this may spoil the fun of it but it seems the cheat is true for series 3.
Disclaimer: I will not be responsible if the information sheet show any inaccuracy as it was taken from external link. This post is just to verify personally against the toy that I have. Nothing more.
So is it a good thing or a bad thing to have such cheats?