For putting Dooku into TPM, I would have replaced Darth Sidious with him and used maybe some voice overs from the clone wars movie. The trade federation has to be re-dubbed whether it's an alien language or not IMO. I think that Dooku should be a main Villain who is constantly in search for a secret apprentice to kill Darth Sidious and take over, that explains why he trained Grievous and Ventress. I think I would make it so that he thinks Maul is dead but then once Ventress dies he goes and looks for another apprentice and ends up finding Grievous (Maul) again. Once Palpatine finds out about Dooku's plans, he sends Anakin to go kill him at the same time Obi-wan is sent to kill Grievous/Maul

Just for funsies, I did this :P