@Slackra
GTA 3 and GTA Vice City are 2 different games! Vice City is newer than GTA3.
The crack you have downloaded needs to be copied to wherever the game is installed. You need to replace the original 'gta-vc.exe' with the cracked one!
Make sure you rename or copy your original file first before overwriting it! You more than likely got the mss.dll error message because you tried to run that nocd crack from the wrong directory!
Good luck.
