I am a member of Jerry’s $10k program and I must warn the world that this program is not what he makes it seem.

Go to Home Depot and ask about the bid room program.  

Are there any lending programs that allow for seller financing of the down payment in 2nd position? 

It depends on the program, the two that I am most familiar with will do 100/100 at 70% ARV but will underwrite pretty heavily and will treat it almost along the lines of a non-QM lenders and might even underwrite the builder/GC.

This is where the science of the program gives way to the art of the investor.

It may require you to maintain a specific liquidity ratio over the life of the loan, or maintain cash reserves equal to a specific number of payments, or upon inspection prior to the loan being Funded, Require you to come out of pocket with cash, for instance, to replace the roof because it has more than two layers on it, replace or grind concrete that has heaved, or embark on a program of replacing balconies that have rotted within a certain amount of time, et cetera...

That can mean a variety of things, and be a number of different loan programs. 

He usually sends me over his buyers who need a renovation program then I send them back if the qualify.

There is a program offered by HUD called "Good Neighbor Next Door".

In my state, TN, the law states that if you do not have a forwarding address, you are to mail the accounting of their deposit to the last known address and if it is not received there the extra deposit, if any, is to be forwarded to the state unclaimed money program.