Maybe I'm missing something, but it seems to me you could just make a module that does the config reading and code the config file location there. When the config moves, you have only one place to change. If you want it to figure out where the config is (from an %ENV variable or looking at the current directory, or whatever), you can do it there there too. Then in each file just has one use line and one sub call to get the config.

Is there something about your situation that doesn't fit this soultion?