Deployment alone is a hassle for VSTO Developers, especially beginners. In this, if one needs to deploy add-in in a 64-bit system is hectic. Here is a simple solution that I have used to debug and deploy add-ins in 64-bit Office.
You just need to follow these steps.
By default, the add-in will be registered with the respective office application. This is enough to run the application in debug mode. If we select ‘my add-in should be available to all users…’ option, it registers the add-in in the 32-bit global registry. This can be seen in RegEdit like this.
But, 64-bit Office cannot see registries in this location. For the add-in to load correctly, the registry keys should be moved to the following location.
For deploying the application…
In Visual Studio 2010, you just need to update the TargetPlatform property to x64 in the Setup Project Properties. Your project is ready to be deployed in 64-bit versions of Office now!
If you are working on Visual Studio 2008, there is a bug in setup project which prevents the add-in from registering 64-bit COM components. A work around is suggested for this problem in Cannot load 64-bit self-registering DLL’s section in Troubleshooting Windows Installer Deployments article in MSDN. It describes how to manually write 64-bit registry keys for making your add-in to work in 64-bit Office.
For more details, go through this article: Deploying COM Add-ins for 64-bit Office using Visual Studio