Synchronous serial

Hey all,
i'm trying to read a Gameboy sending synchronous serial data, but can't get my head around it. I can get the Arduino to send synchronous, but I've ground to halt trying to receive. I know that each bit takes 122 microseconds, but I don't know if there's a wait period between bytes (and if so, how long?) or if it sends like hell. Most of the reference info out there is about RS232, and I'm not skilled enough to filter out the unimportant stuff.
So, what I need help with is the programming of reading the bits, synced with an external serial clock.
A bit more info:

Any pointers and/or help with this would be hugely appreciated!