While waiting for a solution to load the kernel from SD/MMC I have a working image of r121 for CXX0 models that can run from SD/MMC.
To boot it you will need one of the lates u-boot images that can mount root from /dev/mmcblk0p1 (by pressing KEI_1 at boot) and r121 kernel installed on the onboard flash (or something similar of your own build compatible with r121).
If anybody is intrested drop me a line.
