Customize the error caused by the Bootstrapper

I built a bootstrapper for the windows installer (*.msi) file for an application. I is working very well. what i wanted is to customize the error occurred while installing. Here are some errors:

1. This is the error caused while downloading the package from server.
   Download failure

So i wanted to customize this error like, Check internet connection or some other error message

2. This is the error caused while installing the lower version of the installed application. Higher version installed

So i wanted to customize this error like, Already higher version of the application is installed or some other error message

I wanted to display the error message dynamically depending on the error code (0x80070666 refer 2nd image). please help me how to do that.