But all this is assuming you want to copy my arborescence:
arc/
3.1/ # "my" version w/ patchs
3.1orig/ # "official", ORIGinal version
3.0/
...
Maybe you'd better look at the diff and manually apply the patch. A good way to start looking at Arc guts ;-)
This was how I expected interested people to use the diff. But using `patch' directly is a good solution too :-)