I'm terribly sorry for bumping this, but i just found out how to change the trail's colour...
You have yo put "0xFF0000" (for example, that's red. You can check the colour's code on flash)
other example: If you want it to be blue, you put "0x0000FF". Obviously, without the quotation marks.
Again, sorry for bumping, but i did it for the sake of helping. Put me has many infractions you need. *Heroic pose*