While I may have started with Linux 0.11, I've expanded this to include several older relases of the Linux kernel that you can cross compile from Windows, and run on Qemu. I've managed to get the older versions of the software tools running on Windows, so that there is no major invasive source changes, outside of either broken drivers, or massaging the makefiles to find things in the new paths, and calling the appropriate tools where needed.
Linux 0.10 is the first oldest version of Linux...