BiffJTAG allows dumping from and writing to your Bifferboard flash memory. It can write/dump the entire 1MB flash or just the BIOS area. Don't tell anyone, but it's highly likely that BiffJTAG can also read and flash the BIOS area of most other RDC devices (R8610, R3210). BiffJTAG can be purchased from the Buy page.
To connect BiffJTAG to your Bifferboard you are going to need a PC parallel port. You can either buy an Xilinx cable (DLC5 is known to work), or make up the basic circuit below. This is a standard RDC programming cable design, but instead of using the 74HC367 it uses the more generally available 74HC244. This circuit also skips the cable-checking part, because I'm assuming you don't need the software to tell you when you forgot to plug the Bifferboard to it.
The software only supports a parallel port at 0x378. It uses direct IO port access to the port, so please ensure no printer daemons or other software that may interfere with the JTAG operation is running. You need to be root to run it.
Purchase entitles you to updates to BiffJTAG itself, and also Biffboot for a year.