Need Help with PIC as SPI Slave

[PICtron]

Is there really no one who can help?

I think the MSSP module is the one to use.
But I'm really struggling with it.

What registers are to be set and how do I set them?

And how do I sync to the incomming datastream?

Here some more details:

Incomming data is in bursts of two packets (four bytes each packet).
there is a delay of about 200µS between two packets of a burst
and there is a delay of about 200 ms between two bursts.
The clock idles HIGH

I'm planning to use a 16F876A @ 20MHz

Any code snippet or advise will be appreciated.