DS1077 to drive a PIC's clock
This device appears to output a simple 5V square wave, so configuring the PIC in EC mode (external clock) should 'just work'. The clock is applied to OSC1/CLKIN, leaving OSC2 free to use as a GPIO line.

Bear in mind also that this PIC device has an internal PLL, so you should have some flexibility in changing the frequency even without the external clock module. 

The MSSP baud rate is generated from the oscillator frequency, so the BRG value will need to change whenever \$ F_{OSC} \$ changes.