How to configure your antivirus to automatically scan downloads in Firefox
These commands should work for WinZip, IZarc, WinRAR, etc. You may have to surround the path to the executable file in quotes to make this work.
C:\Program Files\Alwil Software\Avast4\ashQuick.exe %1
C:\Program Files\AVG\AVG8\AVGSCANX.EXE /scan=%file% /exe=* /arc /clean
C:\PROGRAM FILES\McAfee\VIRUSSCAN\mcods.exe %1