I found some chr-file to BG1 which enable you to play as Drizzt Do'Urden. It had his scimitars, his armor, and the voice of the Drizzt in the game.
I was thinking of doing something similar in BG2, but with Irenicus instead. The only problem is that I can't understand how I shall find the files that contains his comments (classics as "You bore me, magling", "You live YET?" and "You will suffer, you will ALL suffer!"). Does anyone know how to extract that/those file/s, how to make them wave-format and so?

Try www.blackmagicgames.com/bgseries.html
It has an Irenicus soundset and it is pretty good too!