DS25BR120: Can Pre-emphasis settings PE0 and PE1 be changed dynamically?

Context: We wish to set the PE inputs to DS25BR120 using GPIO from an SPI based IO expander rather than use fixed pull up and pull down resistors.

Question: Are the PE inputs to DS25BR120 sampled at power on or can they be changed after power up to vary the pre-emphasis level?

Thanks in advance.

Stephen