It's been a while since I played the early scenes, I didn't there being too many choices that actually made a difference (sorry if I don't remember correctly). I used the pdf walkthrough to show me when I could get to do the things I needed to do.
I'm not a modder, but I suspect that this would be a very difficult one to mod. It's not a choose A or B and go down that path type of game, it's more repetitive and pretty sure that everything you miss you can do the next time around.
ImperialD will tell me If I'm wrong (he's obsessed with the game and played it over and over many times).