The codes need to be of the assembly kind and will most likely be stored on the PSX.EXE or SLUS/SLES/SLPM file which are pretty much the same. Then when you have the assembly code you open that file in HxD and calculate the Gameshark code and subtract 800F8000 to find the byte array
Lets say...
sorry, beein trying to find this file that's been right in front of me for a month now, only to find broken links, and google to prove that it's completely worthless.