Import LoginToboggan settings
You'll want to use the strongarm module. That will expose the variables that logintoboggan stores it's settings in to features. When building your feature it will add an option for "strongarm: variables" to the edit components section.
You will need to know the actual internal variable name. You can get that by either looking at logintoboggan's code or from the field names in the settings page's html source.