At least it is quite useless to have a thermistor when you do not know the resistance-temperature curve exactly. We have some common types predefined and for others you can define a user table using the datasheet of the thermistor. There you normally find also a more exact table that is not computed from B value. If you find such a sheet for your themristor that would also work for yours I guess, if not it might be easier to buy a known type.
