AD9146 - How do I change the range on the auxiliary ADC used for the die temperature sensor?

The datasheet for the ad9146 is not very clear on how to change the range on the Auxiliary ADC such that the temperature range can be modified.  In particular in the datasheet http://www.analog.com/media/en/technical-documentation/data-sheets/AD9146.PDF, p26 of 56, we see that the register 0x48 corresponds to a Die Temperature Range register, but there is no detail in the spec sheet on how this actually works.  Could someone please enlighten me?