In addition to the good solution by LvW, that's based on the ideal exponential thermistor characteristic, I try to answer the original question.
The first point is to understand the SPICE polynomial controlled source model, that's used for the quoted netlist. You should be able to find the explanation in SPICE textbooks and e.g. in the HSPICE Simulation and Analysis User Guide.
The second point is how to derive polynomial parameters from an empirical resistance versus temperature characteristic. The method is called curve fitting and can be easily performed with a spreadsheet calculator, e.g. MS Excel. Polynomial fit of a given order is an option in the Excel diagram window.