Would this code snip-it from
http://www.spinifex.com.au/plugs/installer.html help?
Flashing the plug with a USB stick
Copy the file uboot.bin to your USB stick, then:
usb start
fatload usb 0:1 0x0800000 uboot.bin
nand erase 0x0 0xa0000
nand write.e 0x0800000 0x0 0xa0000
also using "nand read" to get a copy of the original uboot.bin
# nand read <loadAddress> <sourceAddress> <count>
where SourceAddress is 0x0 & Count is 0xa0000
BigBear59