It's really easy. Head for the Strip where there are loads of chapels. Make a reservation. Jump in a cab for downtown Las Vegas. Find the Town Hall, fill in a licence application, which costs about $35. Once you've got a licence, head back to the chapel where they'll marry you. Good luck
Ross and Rachel did on Friends -- one of the best episodes ever! They didn't do the whole Elvis thing but close enough.
I have heard that there are drive through chapels in Las Vegas...scary.
Yes - go for it. It's an experience. We booked ours over the internet and family watched it over the internet. Just what we wanted. Lots of links on the net to all sorts of themed weddings... try this for starters - http://www.lasvegasweddingchapels.com/
Have fun!