Don't think that can be done easily, no. All names in the game (be they kings, captains, generals or lowly spies) are generated through namelists. Even the names the cardinal_become_Pope "choose for themselves" is just a name chosen at random in the Papal_states name list.
The only thing that could be done would be to allow the player to rename his characters ingame. Since you can rename towns already, I assume it would be possible to enable it for characters as well. Sadly, I wouldn't know how - I quickly looked for something like this in the preferences file, but could only find a param that displays character names under their icons on the strat map (quite handy actually).