The Turkish AKP model comes to mind. The military and Judiciary as well as the moneyed class did not want Erdogan. In fact the courts prevented him from assuming office. So he let Abdullah Gul become PM. Once they had formed government Gul's government lifted the "ban" on Erdogan and it was just a matter of time before Gul became President and Erdogan assumed the powerful post of PM.
What Raila needs to do is identify a principled person and support him. Then have the constitution amended to provide for a balance of power between PM, Parliament and President. Obviously most power should be retained in Parliament. He can then become President or PM depending on their deal and the vote in parliament.
However I have to stress that it is not so important that Raila becomes something. What we need is a cooling down of the political temperature in the country where power is less important and order and justice pillars. Government jobs should no longer be avenues to wealth but step stones to a vibrant career in the private sector.