MSP430BT5190 + PAN1323 Slow Clock

So I have realized from reading other forum posts that indeed in order to have the PAN1323 function properly, you need a crystal oscillator. 

In saying that, I have a custom board made, to which I have a jumper to the clock line of the PAN1323 slow clock. My question is in 2 parts.

First, what exactly is the slow clock line on the PAN1323 doing?

Second, Is it possible for me to run the MSP430 on the internal clock and just run a jumper to the slow clock line with an external crystal for the specified frequency? What I mean is, that does the slow clock need to be driven by the MSP430's ACLK pin or can it be driven separately through an isolated clock from the system? 

I have tried connected a function generator tuned to that frequency, however, the function generator does not work. 

I was also under the impression that the slow clock line could be driven externally, but please correct me if I am wrong.

Thanks for your help