Instructions
Download the gpSP Cheat Creator from a trusted website (See Resources).
Right-click on the downloaded file and extract it to an easy to find location.
Double-click on "gcheat.exe" to start the cheat manager creator tool.
Type your cheat codes into the gpSP Cheat Creator tool using the following format: name of code device ("PAR" for Pro Action Replay or "gameshark" for Gameshark), a "_" followed by the version of the code (use v1 for version one, v2 for version 2 and so on), a blank space, name of the cheat, then press "enter," so that the first line follows a format like this: "PAR_v1 InfiniteHealth." On the next line, enter the specific code you intend to use in a format like this: "XXXXXXXX YYYYYYYY" noting that there is a space between the first eight characters and the next eight characters.
Repeat the process for any additional cheats you'd like to enter for a single game.
Click "File," then "Save as," and name the cheat file the name of the GameBoy ROM you wish to apply the file to in this format: "romname.cht"
Copy the .cht file to the same location as the ROM that will be loaded by gpSP.
Load gpSP and select the ROM you wish to apply the cheats to. Once the ROM is loaded, select "Cheats and Miscellaneous Options" to toggle each of the cheats you created.