Using the CopyAsHtml Addin with VS2008 is not difficult. The standard installer will install to the VS 2005 Addin location. Generally c:\<userName>\Documents\Visual Studio 2005\Addins.
To run this in VS 2008, simply copy these files to the same place in the Visual Studio 2008; I had to create the 'Addin' folder. Then open and edit the '.addin' file and replace the value of 8 in the two 'Version' elements with the value of 9. Then save the file and restart VS2008. That should be all there is to it.