PCM Reprogramming, What are the Barriers

[Kevs02Accord]

Been looking around and was wondering what all goes into developing a system like the hondatas and kpro? I have been looking into pcm reflashing and it seems as if there is no solution, except to go obd1. What are the barriers to the reprogram. If you can connect to the pcm through the obd2 port, why can't you use a program to interpret the data, manipulate it and send it back? What if you took the eprom chip out, replaced / reprogrammed it, is that possible?