not aware if the DKprogrammer is already available but found that you could use a D2pro JTag programmer
sourceThe FPGA and the SPI Flash are two components of Wii DriveKey that can be reflashed and updated: Most updates can be done via DVD as they are connected with writing to the SPI Flash. But just in case an FPGA update is ever needed it is possible to connect a d2prog JTAG programmer to DriveKey.
maybe you find that JTag programmer easier than the not yet released (unsure) DKprog
good luck with your update