When you try to install a Window service in 64-bit by using InstallUtil.exe in the folder C:\Windows\Microsoft.NET\Framework\v4.0.30319, most likely you will encouter the following error:
Exception occurred while initializing the installation: System.BadImageFormatException: Could not load file or assembly 'file:///xxxxxxx' or one of its dependencies. An attempt was ma de to load a program with an incorrect format..
The reason is because you are using the 32-bit version of the tool to install a 64-bit architecture application. you should look for the 64-bit version of InstallUtil.exe here:
C:\Windows\Microsoft.NET\Framework64\v4.0.30319