Ernesto,
From memory, the honda ECU had loads of code in to record faults and driving conditions for warranty and service purposes as well as fault finding, so I think you will find the majority of the code you will not be interested in. I know several people who have attempted this before, and they all failed.
What is the reason for wanting to modify the fuelling map?
Is it

a. You have modified the engine and need to change the fuelling map accordingly.
b. Because you just want to.

b is probably the best reason. I've learned loads of things by doing things with my cars 'because I just wanted to', and then working out why it went wrong.

Anyway, the first thing that I would do is identify from the hardware which pins on the micro are responsible for firing the injectors. This may well be difficult, but once done, you will at least be able to identify the code that fires them.
There will probably be several tables which control the length of time that the injector valve stays open for. There may be a primay map of engine speed and engine load which gives an injector duration. There will probably also be corrective maps which contain values to add or subtract from the duration based on throttle position, engine temperature , ambient temperature etc etc.

I'd give that a couple of days, and then buy a Weber Alpha.