While reading on the topic of plausibility on this website's wiki (I believe it was), I came across a note that if there is a point of divergence after Napoleon's birth, then it should be considered flat-out impossible that Napoleon will be appointed Emperor of Japan in the early 19th century. The notion of a European somehow establishing himself as an Emperor in an Asian country intruiged me. What I am referring to is not the Indian case where a nation was declared a colony and the monarch back in Europe was declared Imperial head of state of that colony, but the Brazilian or Mexican case, where there actually was a nobleman of European origin who ruled a non-European nation with his court and capital in that very nation. So let's say I wanted to have a Chinese Empire ruled by a scion of the House of Hanover, Bourbon, Bonaparte or Habsburg-Lorraine. To make the challenge as difficult as possible, let's put the PoD no earlier than the end of the Napoleonic Wars in 1815. How do I achieve that?
Personally, I am interested in exploring the possibility of having the French join with the British in the Opium War (or a later more destructive war), culminating in the partition of China into new states loyal to the two European nations (for example, a British-backed fully independent Tibet would be interesting). These are then ruled by noblemen and former vassals of imperial China. Soon enough, though, citing obstruction of British and French interest, these new states are rapidly colonized, with Viceroys appointed as rulers. In a later German Unification War, the French royal (or imperial family) flees Paris much like the Portuguese royal family fled Lisbon and arrives in one of their Chinese colonies, and soon, much like the Portugal-Brazil case, we get a French Emperor of China.
Clearly this rough draft won't work, and so remedies are needed to achieve the objective.
Suggestions?