A manual is critical for setting up a bridgeboard. Can't find a digitized one after a quick look, unfortunately. Hopefully one will turn up.
About that floppy cable, though, I seem to recall that it's just 2 floppy cables taped together and one set of connectors goes from motherboard to bridgeboard and the other set goes from bridgeboard to drive. But definitely get confirmation on this before you try it! There are jumper settings involved, too.