Comments - Ancrath

If you're launching the game from the steam library you need to right click on the game and select properties (it's at the bottom of the drop down menu).
Then select Set Launch Options near the bottom of the general tab.
I believe from here the command line is the same as the one Brotap mentioned in his post. I'm not 100% on that however as I do not own the steam version.
I hope this helps.