I could not find the milliVolt input ranges for that specific type of thermocouple. What I did find was that it has a temperature range between -200 and 900 deg C. Since the temperature ranges seem similar to other types of thermocouples, you can compare these to the ones mentioned in Appendix A of the NI-4351 User's Manual (www.ni.com/manuals, and make a search for "4351") in order to get an idea of the accuracy that you can expect.
Regarding the software, there's two options: 1. To use NI-DAQ: with this, you can create a Temperature Custom Scale and use it with a Virtual Channel so that the Voltage readings will be translated into Temperature readings.
2. You can use the NI-4351 own drivers for reading the voltages, and then you can add software tables to your program so that those voltages will be translated into temperature values.