I would recommend that you simply leave it as a .resources
file, as described in this article.
Dim resourceMgr = ResourceManager.CreateFileBasedResourceManager(resourceName, resourcePath, Nothing)
Since MSDN notes that this locks the file, preventing updating an ASP.NET site, you may also wish to make a copy of the resource directory before creating the resource manager. Depending on how and when you plan to update them, you may also wish to keep these resource files under the App_Data folder.