When I ran "make" from the "mydroid" folder, I kept getting this error:
error: gnu/stubs-64.h: No such file or directory
I'm using a 32-bit system, so I don't have a stubs-64.h. The installation guide says 64 bit systems are untested and they recommend a 32-bit system, so that seems like a strange error. Until, we did some looking around online and found out that the command they give on the installation guide points to something other than the stable froyo release (top of trunk, which I guess may be gingerbread or some updated version of froyo?).
Then, I ran this (almost the same, but I specify which version of Android OS to reference):
$ repo init -u git://android.git.kernel.org/platform/manifest.git -b android-2.2_r1.1
It compiled completely this time and now it's time to flash it to a phone!