Can Visual Studio automatically adjust the name of other file as it does with app.config?
See the question and my original answer on StackOverflowI think it's pretty hardcoded for app.config (you can try other names xxx.config and it does not work).
You could achieve the same result without a post build event, but with a custom tool that you would choose for your .log4net files. See these examples: Writing a custom tool to generate code for Visual Studio .NET and Developing a Visual Studio Custom Tool