Use private money lender for down payment on a seller finance?

[Alex Hansen]

So I am working with a seller that is open to seller finance, but they need 10% down payment. I am wondering how it would work if I use a private money lender for the down payment and how I would structure the seller finance deal so I can pay off. 
For context: If we do a standard 30 year amortization, monthly PITI is roughly $1800 and rent is $2400. Down payment would be $30k. All advice helps! Thank you.