For connecting an external TCXO reference, we need to know the specification for the slew rate and levels (Vhigh/Vlow). In the product specs, the clock accuracy is defined, but not the signal specs of the pin. (Sine, CMOS, etc)
In the same scope - in table 24, page 39, pin 17 there seems to be a typo for pin XOP. Description is "40 MHz crystal (or TCXO output if using an external TCXO)" and shall be "40 MHz crystal (or TCXO input if using an external TCXO)".