The %file% parameter is a FDM's need, but I suppose it would be useful to know other optional command-line parameters that could fit the users of FDM.
Moreover, FDM includes a list of default antivirus software, with the option to manually add any other program or to change the defaults for that list. Other popular antivirus softwares, including free ones, are already in the list, but not Avast Home Edition.
As a suggestion to the Avast Support Team, it would be useful to get in contact with freedownloadmanager.org and suggest to their devs to add Avast Home Edition to the list of antivirus software for the next build of FDM, and give them all the ashquick.exe command-line appropriate options. This could be useful for users, but also could contribute to Avast! Home Edition popularity, being FDM free and under GNU Public License.