Visual Studio Icon Patcher allows you to update Visual Studio 2012 with the icons from Visual Studio 2010.
Until someone can find a way to change the icons via a plug-in the only way to change them is through resource patching the DLLs that Visual Studio uses. There are a number of managed and unmanaged DLLs containing Bitmaps and PNGs that are used to style the application. For now only the unmanaged DLLs are part of this process with the managed DLLs hopefully coming soon.No images are distributed with this project. You will need to have both Visual Studio 2010 and 2012 installed to use this.Documentation
I will be posting about the progress of this project on my site
for those interested in following along.