Jenkins Multi Configuration Job needs to dynamically modify app.config on nodes

Question

I have a .net test automation suite that needs to run simultaneously on 6 nodes. I have configured a multi configuration job on Jenkins. The catch is, it needs 6 different app.config values (for example, connections strings, web urls, browsers etc.) for the six nodes. Is there a way I can replace the app.config values just before the MSBuild step? I was thinking of building a console application and keeping it in each node and then calling it as a build step. But I am not sure if that is the best way to do it. I believe there is a native method in Jenkins to do it. Does a Multi job come in handy? Any help or suggestions are highly appreciated. Even if there are some links that could help.