I setup Dreamcast emulation to run TOTD on a Mac last year. It was OK... Not perfect though.

I ended up switching to Speedtype on Emacs, which I've found to be far more useful, and very easy to add exercise and drills.

https://github.com/parkouss/speed-type

There was in fact an OS X version of TotD, called "Typing Of The Dead: Typing Lariat", and it was an universal binary too; I think I still had it on my mac a few months ago.

I don't think it's sold anywhere anymore; you should be able to find it on some abandonware website, with a bit of googling.

The menus are in japanese but the text to type is all either in english or at least uses english characters. If you want the proper english version you could try with wine, the tests on winehq seem to report decent compatibility.