You download the Real CLEO at the official website which is:
cleo.sannybuilder.com and click auto-installer for GTA II all the way on the left, but put the file and folder in the GTA 3 Documentary. And finally, you add the mods to the CLEO folder!
Oh, and how do you copy the models folder in the game? That just doesn't make sense... Do you mean that I should move the TXD file that is inside the folder to the models folder of the GTA 3 Directory? Please answer this fast... I can't wait long!