The modcredits command will modify the local player's credits by the value provided. Here, append ' cheat' to the line, thus adding this option during the process launch of galciv3.exe.
Notice the TARGET LINK, which has the direct path and name of the Galciv3.exe application. For those that do not have steam, you will need to create a shortcut item of the Galciv3.exe, and then right click on it and go to properties. Here, type in 'cheat' and this will be added to the process launch of galciv3. After that, in the default General Tab, click on the launch options button.
Note: If you use steam, go to library and right click on the Galciv3 game, and you will see properties. For information on specific commands type help. If the console has opened, type help to see a full list of the commands. Once done, open the console with the default tilde(~) key, the key can be changed in input options. In order to either write cheats or use other console commands you first have to enable the debug console by adding the -cheat launch option to GalCiv's executable file.