How to find out where patches have been applied to my setup?

Dear all

During the early setup of our current installation of
Eventum, I added som 
patches, and a developer of mine have also made som changes
in the current 
setup, but unfortunately the changes haven't been
documented. I know it's 
a big mistake and I can only blame my self for being so
stupid, not taking 
the time to do it in the proper way, instead of just going
ahead using the 
changes.

Now here comes my question: can anyone tell me how to find
the differences 
in my system, which are not part of the original setup ?

Sorry to disturb you all with a question which should never
had been 
nescesary to ask, but I don't know where else to but it.

All your help is appreciated. Looking forward hearing from
some of you.

kind regards
Flemming Jul