Interesting.. I forked your repository for tested with my exporter.
My level of Ruby / javascript is very limited.. atm
Greetings..

Hi guys..
I add specific code for launch RoadKill from menu option.

For option dialog..

if( not file_loaded?("UVtools.rb") )

	menu = UI.menu("Plugins").add_submenu("UV Tools")
	menu.add_item("Export UVs to OBJ")  { UVtools.start_bridge()}
	menu.add_item("Launch RoadKill")  { UVtools.runroad()} # add RoadKill option
	menu.add_item("Import UVs from OBJ ") { UVtools.return_bridge() }

	UI.add_context_menu_handler {|menu|
		ents=Sketchup.active_model.selection
		sel=Sketchup.active_model.selection.first
		sub=menu.add_submenu("UV Tools")
		sub.add_item("Spherical Map") {(UVtools.new.spherical_map(ents))}
		sub.add_item("Cylindrical Map") {(UVtools.new.cylindrical_map(ents))}	
	}
end

..for launch Roadkill.

## povman; add code for launch RoadKill from the 'menu' option
	def self.runroad()
		# Roadkill arguments ( from RoadKill for Softimage);
		# -lscm or -abf
		# -fillholes or -notfillholes
		# -live or -notlive
		# a tipically command line;
		# "C;\RoadKill\RoadKill.exe" "obj_path,edge_path,-abf,-nofillholes,-live"
		obj_path=self.get_obj_path
		#TODO; create option dialog for arguments..
		roadpath=UI.openpanel("Path to RoadKill", "c;\\", ".exe")
		#
		command_line = "\"#{roadpath}\" \"#{obj_path},,-lscm,-nofillholes,-live\""
		# for debug..
		puts command_line
		# run RoadKill..
		system(command_line)
	end

Greetings..

Thanks!!