Ah, cool. I remember trying something similar but in the end didn't want to bother with the weird template setup.
Edit: Wait, does this install new templates for the "New Project" dialog box in VS or is it just some extra directory with templates in there?
This will install templates for Visual Studio 2015, So when you click "New Project" it will have 2 SFML projects under C++>SFML.
It also installs the lib/dlls/includes in a SFML folder under ProgramFiles(x86) which is linked with an environment variable for the templates to locate the items.
All included resources need to be under the Resources folder some how. I have a post build event that copies all of the items under resources folder to the built path.
while loading an item included in the resources make sure you have the file path included in the string
texture.loadFromFile("Resources/Textures/sfml.png")
Did the installer go to the end for you and the .vsix didnt launch? or did it error out somewhere inbetween?