You can install just the SSDT for SQL Project bits on a machine. That does not require a full install of either Visual Studio or SQL Server. You can generally keep an eye on the SSDT Blog for the latest release news. You can find that at: http://blogs.msdn.com/b/ssdt/
At this time, the most recent release is the October 2013 release.
As noted in the various articles, you may need to make an Administrative Install Point if your target machine does not have internet access. Follow the instructions in the article and you should be fine.
I've written some articles about this on my blog at http://schottsql.blogspot.com if you look up the label for SSDT.