Nope, I just download and run them as I need them. If you want to run multiple instances side-by-side you'll need to find the FirefoxPortable.ini file in the source folder and drag it to the location of the FirefoxPortable.exe file. Then open up the INI file and change "AllowMultipleInstances" to true. I also change the option above that one to true because that will disable the splash screen.