But would a player have to set that up, or does a modder set it up once, and the user only needs playonmac and the file the modder created?
The user only needs PlayOnMac/PlayOnLinux. The Masterwork Dwarf Fortress install script would be in the PlayOn* repository, so everyone with PlayOn* would be able to install it, just by selecting it from the menu. Before it hits the main POL/POM repo, users can download and run the installer script itself. But well-written scripts are almost always accepted, because PO* aims to make it easy to install and play as many games as possible.
You will need someone with shell scripting experience who's willing to become familiar with the
PlayOnMac Scriptwriter's Documentation, but they don't need to know anything about modding DF itself. It's all "download this file, unzip into this directory, make sure dotnet40 installed, make sure we have this version of wine" code.
The main gotcha is that Dwarf Fortress and the Masterwork settings programs work best under different versions of wine (1.2.3 and 1.7.7 respectively). Someone may be able to find a version which works with both, but I haven't found the dfhack window to display properly in more recent wine releases, and I need the dfhack window to live.
(One can probably work around this just by having two installers/menu items, one for 'MWDF Settings', and the other for 'Play MWDF')
~ T