That usually means there was an error when making the client. Try opening the mod selector through the terminal so you can see the debug info. Likely when you build you'll see a bunch of error text pop up. I'm not sure it is possible to get the mod selector to work through a change of the .ini file. I think some of the functions used inside it are platform specific (i.e. windows only). If I had access to a mac computer I would look at this but I don't.
Maybe I'll make a hackintosh and give it a go but I'm in no rush to do so.