Sometimes you need to call gacutil or other SDK tools from build-events and in order to do this, they need to be added to the path.
Not exactly rocket science, but I always forget the macro and for future reference the following line will do the trick:
call "$(DevEnvDir)..\..\VC\vcvarsall.bat" x86
Christian Staerk
a589308d-8875-4dc7-8296-8120a2d2a2d1|0|.0
Visual Studio 2010, .Net