serbia is a monarchy,ruled by a conservative party.it's realy dificult to do anything without cheating
Cheating is necessary when overcoming limitations in the game engine. A rebellion in Serbia against the Ottoman Empire wouldn't be restricted to the 3-province micro state, but the entire Serbian region, meaning both Serbia as a country and the regions of which the Ottomans are holding.
So what I would do is:
1. Neville
2. Get all the Serbian Lands from the Ottoman Empire
3. Roleplay it as Serbia getting more autonomy in the Ottoman Empire, or simply roleplaying Serbia as a province as opposed to a seperate state
4. Declare a 'revolution', therefore the entire Serbian state, which is 'newly independent' is in hostilities with the Ottoman Empire. Just think like how the CSA in the game is independent prior to the civil war occurring.
Of course you might know that Serbia has like almost no events in the game. So you'll have to edit saves in order to add cores and South Slavic cultures.
When it comes down to, this is by no means cheating at all, nowhere as bad as the guy who was playing as the Dutch East Indies and adding anything that was more than 10% of the population as national cultures