Look under "Visual Studio Tools" in your start menu -> Visual Studio,..
There should be something like visual studio command prompt,..
If you start that, GACUTIL get's added to the path and is availible as a command.
Thank you for the answer. But the fact is that it isn't. After searching I have found that something is wrong with the installation of Visual Studio so I'm uninstalling
now and in one hour I will know if is there where you say