Im guessing you are a windows user?
right-click the dom3 icon that starts the game,
scroll down to properties, then look at the line that says "Target". Add switches to that (after the quotes if there are quotes). I think its -f that you want to add.
Here is a list of all the switches
http://www.dom3minions.com/docs/CommandLine.txt
Here is what Ive got on my Dom3 icon
-fwacd --magicsites 65 --renaming --indepstr 7 --hofsize 15 --eventrarity 1