Replacing exec is a pretty difficult job because it is so central and early in the system. SetPatch with BoingBag 2 does it, though. expansion.library is also the only lib that cannot be replaced by the exec mechanism (only custom ROM), but all other libs can easily be "updated" with the LoadResident mechanism (KickPtr/KickTag). Damn clever. I think the actual mechanism is available since the 1.x kickstarts (don't quote me on that though)... There might be some slight differences especially between 1.x, and 2.x...
