I really have to read the works in question before I can comment intelligently (or otherwise ;o). I've heard of extra-canonical writings that speculate about the preexistence of the messiah. Is this the sort of thing you are talking about? Or is it more specific?
Yes, specifically Enoch. Jesus' half brother Jude quoted in the New Testament a prophecy by Enoch from the intertestemental writing of Enoch. Apparently some jews in the first century thought that book was scripture.