with Ched80's plug out of the way.
You need to create a system within the setuplevel.fpi file located in the
Files\languagebank\english\gamebank\mygame\ Folder (mygame is the default folder for the test game, if you already created a new folder then it would be whatever name you gave it.)
The add-on to the script will need some HUDs with a few dimvar and a little bit of the etimer and such. (This is something I have sort of done before.) In the end you will end up with something that might be easy to use with just a few scripts for pick-ups that allow for you to lower or raise said stats.
If you decide not to go with the amazing RPGmod. Then you either need to get
FPI EditPad with
Ched80's Complete Script Syntax List and start learning how to script, or find someone that is willing to do it for you (depends on what's going on in the scripts forum).