When you go to change the icon you can "add an icon" (see upper right of that icon gallery dialog box). It'll ask for the URL of the icon you want to add. To get the URL of an HF 'hanger" icon, right-click on an existing icon on the map, choose "copy image location" then paste it where requested. Select the new icon and then close the placemark edit box. Click on 'Save' and 'Done', if necessary, and you should be set.