Hi Dahjah,
You should only need BNC going from the word clock out of the VS and into the word clock in of the Liquid Saffire 56. You will need to set the sync source for the Liquid Saffire to wordclock in Saffire MixControl. Also, make sure that you have routed the analog inputs to the ADAT outputs in MixControl and then select Save to Hardware from the file menu. You will want the VS clock set to internal.
If you wanted to use an external clock generator, connect it's outputs to the wordclock inputs of both devices. Set both devices' sync source to wordclock.