Unfortunately I can't give you a tested how-to. I extracted plausible uImage and rootfs binaries (including interleaved OOB data), but flashing them caused my device to stop booting. Interestingly the rootfs on my device seemed to start at page 8512 (not 6144 as suggested by the OI wiki).
Then I tried the firmware upgrade from rapidshare, following the instructions on the wiki. Same result - I think the LED turns on when booted, but the screen remains blank.
I
was able to flash OI 0.2, so fortunately I can still use my device :-). (I did have to fiddle a little; see
my post on the -user mailing list).
If you're still interested in my scripts, just let me know where I should send them.