yea guys im having the same problem with the mount command. i get this:
C:\>adb shell
~ # mount -o remount,rw -t yaffs2 /dev/block/mtdblock3 /system
mount -o remount,rw -t yaffs2 /dev/block/mtdblock3 /system
mount: mounting /dev/block/mtdblock3 on /system failed: Invalid argument