I am running Windows 8 x64 and have Visual Studio 2012 with the latest update and Visual Studio 2013 preview (latest update) installed. I also have the Windows Phone SDK for
For future references, I installed the Visual Studio 2013 Professional edition where the Windows Phone 8.0 SDK apparently wasn't included in the default installation. I browsed to the Windows Phone Dev Center to download the SDK but this way doesn't integrate with Visual Studio 2013 as well - it surprisingly put Visual Studio 2012 Express edition on the PC...
The only way to be able to incorperate the Windows Phone SDK is by modifying the installation of Visual Studio 2013, just as the OP states.