Trying to debug an installer class was virtually impossible until i came across Josh Robinson's blog
here
.
How you do it is this :
1. Place a breakpoint in your installer class.
2. Just before the break point add this line
System.Diagnostics.Debugger.Break();
3. When you run the installer... i.e. when you try to install, the installer will give a message with an option to debug. Click the debug button and select your already open Visual Studio and select Yes.