Basically, you'd rent out your points to someone (the going rate is $10-$12 per point - unless you're in a hurry to rent them due to expiring points or what have you in which case some rent for more like $9 per point). You'd then take the money from the points you rented and just book cash for the cruise.
As for risks involved, yes there are risks on both sides...you the renter, that you won't book your points and then have the rentee cancel on you and depending on how far (or not so far from the reservation time) you could be in a situation where those points need to be used or lost. And them, the rentee that they won't pay you for a points rental and have you run with their money (the rentee has no control of the ressie whatsover ~ only the member can book,change things,cancel and whatever is necessary on the ressie). If you book the points for the person renting from you far enough in advance,collect the money and make your refund (or I should say NON refundable) policies known before entering into the deal, you should be safe.
i.e. have a contract and/or deal with all your terms met and agreed to up front. You may want to say something in your terms about NO REFUNDs past 31 days out which would be the point your points would then have to be rebooked and used before the end of your UY if they were to be canceled. Plus whatever other terms you may have.
Or any other way you may want to set up your terms. But make them all known ahead of time
I don't know anyone who would be interested in renting.
While it would be ideal to rent to someone you know, you can always hop over to the
DVC RENT/Trade board here on the Dis and just post that you have X amount of points to rent and for how much per point you want to rent for. Check it out..it will give you an idea of what everyone who is renting is renting for. I'd also hop over to the DVC RENT/Trade board and read the
FAQ at the top of the board as I'm sure that will probably be much more of a help to you then how badly I'm probably explaining things even though I'm trying to help
Best of luck!