There has to be some animal rescue or feral rescue organizations within your area? You would be amazed at how many people are out there who will help you.

What about your vet? He/she may know of an organization or person. If the cat has spend 8 years (!) under the bed, I don't see it getting along with your other cats. Also, do you have the time to invest in a feral cat?

I would vote to find an organization or person who has experience with feral cats.