I doubt that it would work. The ATA/Firewire bridge chips are probably not designed to work with a master/slave configuration for the hard drives. I recall reading in the specs for a vendors FW-ATA bridge that it would only support one drive. I am going to assume that is the case with most of them. Some of the bridges don't even have standard cable connectors; etc they plug directly into the back of the plug on the hard disk drive. I am also going to assume that even if the bridge could support multiple drives; the firmare on the bridge chip would have to be written to handle it. . . .Most companies buy these units and do this themselves.
so probably no.