Change Informations FirefoxPortable.exe

there are several ways, depending on how you use it and what you intend to do with it.... the brandmark things are discussed here many times
if you want to change the look for personal use the easiest way is to edit/ replace the appicon in appinfo folder - restarting the menu will show the new icon..
advantage: nothing is messed up, you could leave the original icon renamed where it is and roll back easily if there were problems with your new icon..
the more difficult way - if you use the launcher standalone you should manage editing the icon by uncompacting the launcher by John´s appcompactor and then using reshacker..