I think Sifo-Dyas is exactly who he is said to be: a Jedi Master who died almost ten years ago. Now, he might have been killed by Dooku or Palpy, but all in all it seems like Palpy or Dooku placed the order probably immediately after or just before Sifo-Dyas' death. That way the order would be placed by a credible Jedi Council Member (who never showed up in TPM though).