I have tested Island Rum for Mac with the new Homecoming Launcher, and have designed two different ways that Mac players can use it. The first has been well tested; the second is in early testing stages, but should work considering that it's far simpler.
1. If you don't have Island Rum installed yet, download it from https://islandrum.eekstudio.com/ and extract and install it.
2. After Island Rum downloads the Game Client, stop the initial file download by clicking the red X.
3. Open the tree menu and select Manifests, and then add the following: https://islandrum.eekstudio.com/manifest.xml (might be replaced with alternate URL before this is published).
4. Wait for a short download to complete, and then click the Play button. You will be presented with the Homecoming Launcher.
5. Follow the usual instructions for using the Homecoming Launcher.
1. Download the Mac Installer from https://islandrum.eekstudio.com/mac-installer.zip
2. Extract the Mac Installer and launch it. It might require an administrator password. Wait for it to complete.
3. Launch the Homecoming Launcher by double-clicking the new "Launch CoH" icon inside the Applications folder.