Its the same "Tool" that you use to delegate Steempower from one account to another.
You can go to "collection" on your SM account and than click a card of choice.
You will see different options what you can do with your SM card e.g. Gift, Sell or lease.
If you click "lease" than you can decide who you want to lease it to. Right now everything is manual but peakmonsters is working on a automated lease/rent market where you will determine your lease and rent data.