This mod is a small script that patches a function in the maxis game code to enable additional debug cheats. It also always enable cheats without needing to use the testingcheats command.
The python source is included as it provides an example of how to replace methods and functions in the maxis code.
I do not guarantee that the mod won't break with future updates of the game or that I'll be able to be arsed to fix it. But hey, you have the source :p
Unlike the original less than subtle method of modifying python33.dll to force the __debug__ variable to true, this one doesn't seem to be suffering from any game breaking side effect (at least it didn't during my extremely thorough 20 seconds test of getting a sim to fish and then successfully cancelling it).
Read more and download at Mod The Sims