By 'install e-smith on a Mac OS X machine', do you mean attempting to apply e-smith to the existing underbelly of Mac OS X... or do a reformat and start fresh?
In the case of the former, I strongly suspect it would be more pain than what it's worth due mainly to the fact that Apple has already got a whole string of applications doing basically the same job as e-smith. (ie. Providing an easy to interface to system maintenance). You'd be fighting the upper layer of the OS all the way.
For the latter case, my pick would be an existing stable Mac Distro like Yellow Dog (yellowdoglinux.com) for your starting point. I'm not sure how far YellowDog leans away from RedHat in file layout, but I imagine it couldn't be *too* far... surely?
Best of Luck.
Regards,
Luke