The creation of SSMS add-ins is the black art. Why? Because it is not or very weakly supported by Microsoft itself.
Microsoft has documented official position on SSMS add-ins and extensibility in the Denali BOL, which is also copied below:
SQL Server Management Studio is built upon the Visual Studio Isolated Shell, which inherently supports extensibility (add-ins/plug-ins). It is possible to tap into the Visual Studio extensibility services to surface custom capabilities within SQL Server Management Studio; however, such extensibility is not supported.
There are some users and third parties that have developed extensions to SQL Server Management Studio. While we do not discourage this, keep in mind that such extensibility is not supported, so there may be issues with backward/forward compatibility. Microsoft does not publish documentation for extending SQL Server Management Studio. There are, however, community blogs and sample code that you may be able to leverage.
Microsoft does not support SQL Server Management Studio installations with SQL Server Management Studio extensions present, so if you have installed SQL Server Management Studio extensions, you may want to remove them before calling Microsoft Customer Support about a SQL Server Management Studio issue.
Microsoft simply does not want to support backward compatibility of add-in API between different SSMS versions. There were already two breaking releases. It was an update from SSMS 2005 to SSMS 2008 and from SSMS 2008 to SSMS 2012, not to mention a small jump from SSMS 2008 to SSMS 2008R2. The current version of SSMS 2012 leads to a standard DTE environment of Visual Studio (source: Solutions Crew GmbH).
It seems that this step will bring to developers transparency to the development of SSMS add-ins.
On the web, there are some tutorials, but these tutorials are focused on a specific version of SSMS only and do not reflect the differences between particular SSMS versions. The below link gives you a complex source code that will help you in the building of SSMS add-ins across different SSMS versions.
Feel free to take the SOURCE CODE as a SSMS add-ins skeleton of {3S} SQL Smart Security SSMS Add-In from the CodePlex repository for the building of your SSMS add-ins.
- Building a SQL Server Management Studio Add-in
by Jonathan Sayce - Building a SSMS Add-in; The Agony and Ecstasy
by Mark Pryce-Maher - Extend Functionality in SQL Server 2005 Management Studio with Add-ins
by Ameet Phadnis - Extend Functionality in SQL Server 2005 Management Studio with Add-ins
by Jasinski Technical WiKi - How To : Create SQL Server Management Studio Addin
by Shai Raiten - The Black Art of Writing a SQL Server Management Studio 2005 Add-In
by Joseph Cooney - SQL 2008 R2 Breaks SSMS Addins
by Jonathan Kehayias - SQL Server Management Studio Add-In for Denali\SQL2012 (SSMS Addin)
by TSQLTidy - SSMS Addins
by iucon
Placko's database KB 