Question: I was wondering if there is any script that will allow one to limit the network bandwidth (download\upload) for a certain process on a mac?

Answer: 
The first .NET version of Visual Studio was internal version 7.0, so I think they named the folder Common7 based on that. Then later there were a lot of dependencies (probably external, like plugins or whatnot) that used the name Common7 so it would break too much if they changed it in later version.
There are too many add-ins and build scripts that have hard-coded the "Common7" folder name. Somewhat self-inflicted, it isn't that easy to find the proper path to the folder. The environment variable name is VS90COMNTOOLS for VS2008. Note the version number in the name, also not sure if it was available back in VS2003.