So I have to say that I was pumped up when Microsoft released the new 1.2 extensions for SharePoint (with Visual Studio 2008 support), but then had the air taken out of me when I went to run the extension setup only to find that it was not support on a 64bit platform. Now I have to get on my soapbox here a little and say that, with Microsoft pushing extremely hard the 64bit architecture I find it a little puzzling that they wouldn't release a 64 bit version of these tools. If you think about it, they have 64bit versions of SharePoint, and to now, if you were doing any SharePoint dev you are typically going to have a whole SharePoint rig locally for testing purposes. So again I ask, why wouldn't Microsoft release a 64bit version of these tools?
Ok, enough of the soap box, on to the meat of this post, actually getting the toolset to install (and mostly work) on a 64bit machine. NOTE: This is not officially supported and I have not fully tested debugging yet, so please use at your own risk.
In order to do this you will need to download the ORCA msi editor available here.
Step 1. Download the VseWss12.exe from Microsoft site. You can get it here.
Step 2. In a command prompt window, navigation to the directory where you downloaded the extensions. Once there you will need to extract MSI from the executable you downloaded. You can do that with the following command
VSeWSSv12.exe /extract:c:extractedVSE
Step 3. Once extracted, you will notice that there should be a file named VSeWSSv12.msi in your extracted location. This is not the file that we will be running through ORCA to remove some of the 64 bit dependencies.
Step 4. Start ORCA.exe and open the file VSeWSSv12.msi from the extracted location.
Step 5. Once the msi is loaded into ORCA you should see the following.
Step 6. Navigate to the CustomAction node in the left hand column and select it. You should see the following 
Step 7. In order to get enable 64 bit installation you will need two delete two keys located in the Custom Actions key.
a. Delete the X64System key shown on the right hand side of the application. (Shown below)
b. Delete the WssNotInstalled key shown on the right hand side of the application. (Shown Below)
Step 8. After deleting the specified key, you will need to save the changes back to the MSI. You can do this by Selecting the File->Save menu within the ORCA tool.
Once you have saved the MSI you can now execute it like you would any MSI application. Here are some screen shots of the fully functioning VSeWSSv12 extension installation.
