Ahh, this is the best question yet..
What you will have to do is go into the scripting/coding of RPG Maker XP itself, and modify the graphic recognition script. Which in generalization I mean remodel the graphic recognition script from 4 columns or columns to 5 or how many more. Also I believe while I was searching on google for some scriptings for my small MMO that there was some script that over ride that default graphic recognition script.