Resource files are for localization of strings not for property storage. I would think of using a custom xml config file for things you want to be able to change.
The only thing is in order to resolve the path to your custom config file so you could read it using system.IO classes or XmlDocument is that you would need a reference in your business layer to System.Web, so that you could resolve the path to your file like this:
string pathToFile = System.Web.Hosting.HostingEnvironment.MapPath("~/pathtoyourcustom.config")
then you can open it as xml and process it.
Hope that helps,