Mackey,
As you have the 757/767 on your licence you are considered type-rated. IF they can pair you up with another type-rated pilot then the course is very slightly shorter as you don't need to do the 767 groundschool (although you will still do performance etc) and you don't need to do the type-rating test in the sim. You'll still do all the same air law, radio, emergency stuff etc. In total you may save approximately one month if you're lucky but if there's no other type-rated pilot to partner you then you'll be along for his ride and just twiddle your thumbs while they do groundschool.