I don't have the manual but trying to envision what it looks like from what i saw in my older manual. If the parts are not too slippery yet or you can clean them very well, this may work=
Glue the seals to the pipes on the inner surface with super glue to keep them in their pace. Then when it is tight put some RTV on the outer surface of the rings to help them slide into the head bore. The RTV will also give it a bit of added sealing when it sets up.
Glue the seals to the pipes on the inner surface with super glue to keep them in their pace. Then when it is tight put some RTV on the outer surface of the rings to help them slide into the head bore. The RTV will also give it a bit of added sealing when it sets up.