if you want an easier solotion to this problem get yourself 7 or 8 thin strips of aluminum, 1in wide, about 6 feet long. you can cut them to length and arch them accross the roof, sticking the ends behind the trim peices on the edges.  it works really well and looks good too.  and best of all its cheap and easy.  if you're looking for an easy way out that doesn't cost hardly anything i'd go this route.  that is unless your too good for it adam??? 

dave