Well this was pretty easy with the new patch. Focus line infantry and queue napoleonic warfare.
Build a wheat farm so your plebs don't die, ask for mil access through kabul to snipe the right state on herat. Once you got 5-6k troops you should be able to take over kunduz up north, then maimana.
Negotiate treaty with qing for transit rights and build a trade center in southern turkestan. Betray kabul and give persia the small hazaristan state you took earlier for them to help you.
Then once you fully annex kabul wait for line infantry and then kill persia for all the provinces. You can also get 2K/week for selling transit rights to the sikh empire.