Not sure if this is useful to anyone else - but this is hard found knowledge I don’t mind sharing!
When setting up ITB’s with Alpha N (TPS load) - there are big changes in fueling at small throttle increments, and from what I have read (and experienced) it pays to set up your fuel table with many increments at the smaller throttle openings. If you don’t do this when you open the throttle the AFR will end up being lean or rich during the transition and give poor throttle response or stumbling. Particularly not nice on your daily around town.
MAP based systems (like the standard Charade ECU) for ITBs are not recommended, the main reason being that often with an ITB setup the intake pressure will be the same for varying throttle angles and give poor fueling.
Megasquirt S1 has 12x12 fuel and spark tables, and uses raw ADC (voltage data from the TPS) which I have converted into %TPS opening. I set my tables up with the following increments - see below.
The more advanced MS2 and MS3 use % and have bigger tables - lucky you if you have one of these over the MS1.
Here are my fuel, spark and AFR target tables (this is a reasonable road tune, the fuel map still needs some work in some infrequently used places):
Some other pointers - make sure you get the right sized bodies for your engine. For my car (1.6 HD) I got 38mm diameter GSXR600 bodies. I had read many reports of these being used in Peugeot 106 1600 motors. Smaller bodies will give more low down power and better response. The other thing to get right is the correct intake length - too short will rob you off low and mid range power. The intake length is measured from the back of the intake valve to entry of the intake trumpet. Also be aware that just running the ITB with no trumpet will normally result in too short an intake length and poor mid range power.
For my car I am running a 425mm intake length, which is quite long. Somewhere between 350 and 400mm seems to work for most people. There are a number of online calculators and charts, but the best way to get this right is to experiment with a dyno.