The only MLS that allows Contract Owner Listings is REIN (Virginia Beach/Hampton Roads) area.

On Contract Owner listings:

1. You need to send us a copy of the contract the "Contract Owner" has with the seller.
2. The listing will go in the name of your company in the Seller field
3. Under disclosures, check Contract Owner. 
4. Sign everything with the your name and your title (ie: Attorney-in-fact") within your company.