If you are a glutton for punishment you could write a custom script that takes your file in and writes out a NameMapping.tcNM, but I don't see what the point would be.
If you're using Javascript (or another scripting language) you could read in your separate file and use the eval() function to substitute in the correct NameMapping and xpath values.
e.g.
function ReadObjectFile(filename) {
// read the file in here and return an object with your mapping
}
all_objects = ReadObjectFile("path/to/file")
button_object = all_objects["button4"]
eval("Aliases.App.mainPage." + button_object).Click()
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Senior SQA Automation Engineer
