If you run this command when you’re choosing a site for embark, you can bypass any warnings the game gives you about potential embark locations. Want to embark in an inaccessible location on top of a mountain range? Go for it! Want to try a brief existence in the middle of the ocean? Nobody can stop you! Want to tempt fate by embarking inside of a necromancer tower? !!FUN!!
Any and all consequences of embarking in strange locations are up to you to handle (possibly with other armok tools).
The command will only work when you are on the screen where you can choose your embark site. The DFHack logo is not displayed on that screen since its default position conflicts with the vanilla embark size selection panel. Remember that you can bring up DFHack’s context menu with CtrlShiftC or the in-game command launcher directly with the backtick key (`).