Best way to keep my cat from scratching my mom's couch?

In a couple of months, my mom will look after my cat for a few weeks. She has a brand new couch that means a lot to her because she had to downsize to a small place. Is there a way to protect her couch from my cat? He doesn't tend to be very scratchy but I need him *not* to scratch her couch if she's ever to agree to look after him again after this. I wonder if, aside from Soft Paws or deterrent sprays, if there's anything else she can use. (Are there special covers for couch ends, for example?) I don't really know much about any of these things, so if anyone has advice (both dos & don'ts) I will be eternally grateful!