Short sale with additional payment?

[Eric C.]

I have a deal where the best way for me to buy the house would be to convince the homeowner to do a short-sale and then give him a "consulting fee" afterwards.
How would I do this exactly? Would I write up a Bill of Sale for consulting service on xyz and sign it with him at the same time we sign the Purchase Agreement and everything else we plan to send to the bank? I know this can't go on the HUD-1.

Also, I have a template for the BPO report on file, but I've never done this - do I wait for the bank to call and send out a BPO agent and meet him/her at the house to show it (and show comps/damages)?

Any other tips would be so very much appreciated!! I'm just starting to try the whole short sale process.