Create a tool for the end user to create executables for Mac & PC.

Hi. We need to have a tool created for the end-user to modify existing variables and create an executable that will work both on a Mac & PC. The tool will need to load a custom desktop wallpaper and launch a URL. The trick is that the end-user will need this as a tool to make changes depending on the customer. Is this something that would be possible? And can it be developed to work on Mac...but still have the capability to create executables that will work on a Mac & PC? Thanks.