Microsoft's done a fairly good job in packaging for Visual Studio templates. Simply:
- Create an xml file that adheres to the Visual Studio Content Installer Schema Reference
- Rename the xml with a "vscontent" extension
- Place the vscontent file and your template zip into another zip file
- Rename that zip file with a "VSI" extension.
Now, when you double click the VSI file it runs a wizard that installs your template into the appropriate Visual Studio Template folder.