To solve this problem, I created a Visual Studio Extension which will install the templates that we shipped with VS2012.
Note: This Extension is by no means supported by Microsoft. It is something I created in my own spare time to make it easier for WebForms developers using VS2010SP1 to use the updated templates that we shipped with VS2012
http://visualstudiogallery.msdn.microsoft.com/ec79e369-51bd-4212-83d0-71349d038461 has more details about the Extension and also what SKUs are supported.
Please do give feedback on the VS Gallery for the extension.
This post has been cross posted at http://blogs.msdn.com/b/webdev/archive/2012/10/29/asp-net-web-forms-application-2012-templates-on-visual-studio-2010.aspx