Setting up Visual Studio 2008 for Compiling 64-bit DLLs
This step should be simple. Run the Visual Studio 2008 SetUp program and check the “X64 Compilers and Tools” option under Visual C++

However firstly don’t run the set up program from the DVD or from an ISO on your hard-disk or you’ll end up with the following error:
‘A problem has been encountered while loading the setup components. Canceling setup’
You need to run the Visual Studio set up through Add/Remove Programs. However once I’d selected the components I got the error below – “A selected drive is no longer valid. Please review your installation path settings before continuing with setup.” Of course there is no option to review or even see your drive settings…

Thanks to this thread, the solution was to uninstall Visual Studio SP1 through Add/Remove programs (check the “Show Updates” box to see service packs and hot fixes for various programs).

Finally I got the 64-bit compilers installed, and could begin trying to compile PyISAPIe for a 64-bit processor which is a whole different set of problems.
[...] Studio 2008, and a number of other tools that are detailed as I go along. I’ve also got the 64 bit compilation tools installed. There are a few notes from Phillip on compiling it for Windows 64-bit in the discussion lists (see [...]
geographika » Compiling a 64 bit Version of PyISAPIe
16 Apr 10 at 12:11 pm