Battery charging and the NTC

I have a LiIon battery with internal NTC of 10k. I want to connect this to the WMP100 for charging. In the PTS it mentions that R1 and R2 are used to set the bias, but the level to bias to are not explained. It mentions that R1 and R2 needs to be calculated, but to what answer. The NTC in the example is a 100k and i am using a 10k. Any help would be appreciated. Another question: I see that the T1 is bipolar transistor, can i rather use a FET for size restrictions.