If you're referring to the page I wrote on maemo.org, I only built my own version of fdisk because I didn't have an MMC reader handy

You can reformat the RS-MMC card under Linux quite easily. I gave myself two partitions, the first one standard FAT and the second one ext2. The 770 mounts the first partition normally, so it looks like I have a 2MB card. In xterm, I type "mount /dev/mmc<blah>p2 /sw" (or wherever you want to mount the second partition) and it's there. It's not actually that hard.