They should be interspersed through various episodes like the bald man on Fringe ... in a manner that leaves you wondering if you really did see them .

In Episode 4-17 "No Exit" Ellen Tigh is revealed to have resurrected on board one of Cavil's Basestars after her poisoning. Their past is also revealed: they lived on Earth 2,000 years ago and were researchers in rebuilding Cylon Resurrection Technology which had been abandoned when the Thirteenth Tribe gained the ability to procreate. Saul and Ellen were married even back then and Tyrol and Tory Foster were in love with plans to get married. They learned of the upcoming holocaust from beings only they could see and worked to rebuild resurrection. They succeeded and placed it on a ship which they left in orbit of Earth. When the nuclear attack happened (according to the writers, an uprising of their own Centurions that apparently destroyed both sides) and they were killed, they were reborn in new bodies on that ship in orbit. The Five then headed for the Colonies to warn them about making artificial life, but the trip took thousands of years due to there being no FTL drive on their ship. Due to traveling at near light speed, time dilation made it seem like less than that to them. They arrived during the first war and made a deal with the Centurions: stop the war and they'd help them build human bodies. Thus the Final Five ended the first Cylon War. They built Number One (Cavil) and he helped them build seven other models, but murdered model Number Seven and prevented any hope of resurrection for him. Ultimately Cavil locked them in a compartment and evacuated the oxygen, killing them. He then boxed them and apparently removed the memory of their identities from the other Cylons. He later unboxed and resurrected them, but first blocked their true memories and implanted false ones. Cavil periodically seeded them among the human populations starting with Saul, and eventually Ellen, to show them how bad humanity supposedly was

In "Sometimes a Great Notion", it is revealed that all of the Final Five had previous lives on Earth, 2000 years in the past. As each of them explores the ruins, each begins to regain memories of their past lives. It is when Saul Tigh remembers his previous life that he discovers that his late wife, Ellen Tigh, is the fifth and final Cylon. During Saul's flashback, his wife insinuates that she had previous knowledge of the destruction of Earth when she states that plans have been made for her and Saul to be re-born.

I wouldn't mind the Coffee-shop scenario. I got a kick out of the cameos of Ellen, Sharon and Ron Moore on the recent send up of "Trek" on CSI. My wife had no idea what I was talking about, but she never does :)

L'Emmerdeur is speaking as though the Baltar or 6 'Angel', so 'God' would be correct :)

I think I'm missing something. If the skinjobs are a results of the peace treaty of the first cylon war, and it took place 40 yrs before BSG, how can the Final 5 be 2,000+ yrs old?

You mean the Gods.

Didn't the story say that they came to the cylons during the first war, exchanging the ability to do the 'skinjobs' with the peace treaty?

Wouldn't really make sense to have them before that, would it?

It brings up the obvious plot hole as to how they managed to survive for all those years on the colonies and not notice that they weren't aging!

Or we could just let God decide whether they will be on Caprica.

I don't mind them making a cameo - but I do not want them to become a A or B plot of any episode. I think it'd be cool if just randomly the final five are at a coffee shop with Cavil chatting it up or something like that.

I gotta say no. I've seen Caprica and it's very very strong. It will do well if it stands on its own, and I don't think it will be able to do that with cylons (esp. skinjobs) forced into the timeline.