I forgot to attach the .config file. My mistake.

Anyway, here is the .zip with all files (.config included).

Later I'll try to follow this guide again. If any modifications arise, I'll be posting them here.

See you!

Thanks to this post, some months ago I could successfully install the rt-11 with the 3.8.13 kernel patch in RPi. I attach the procedure I followed with the required sdhci.c file. Thank you!