That is brilliant, we are always grateful for people to add new content.
It is possible to get the VS plug-in to work on VS 2008 / 2010 (although I will have to make a note to see if the developers can release a proper new version).
If you install the plug-in and then copy two of the files that are installed - PInvokeDotNetAddIn.AddIn and PInvokeDotNetAddIn2005.dll - to the folder
<My Documents>\\Visual Studio 20xx\\Addins (or the folder you store your add-ins if you have changed you VS to look in a different place for add-ins).
If you then open the PInvokeDotNetAddIn.AddIn in notepad or similar and edit the two "version" tags from "8.0" to "9.0" for VS2008 or "10.0" for VS2010