You actually can extend out MSBuild to use alternative compilers.
It already comes with rules for C#, VB, C++, F#, etc. Replacing the rules for C++ with another command line and set of parameters of quite doable! :)
(I happen to be using such a build system, unfortunately I wasn't the one who wrote it so I cannot provide any direct help, just encouragement!)
It can actually all work from within VS as well.
... and msbuild was recently open sourced. The code is right there on Github.
Yeah, Microsoft of 2015 is very different from Microsoft of 1995, in good ways.