Yes. On a plane which is designed to be a good glider. I highly doubt a 767 is designed to be a glider.
It's definitely not impossible (after all, it was done successfully!), but certainly a very difficult (and undocumented) one on such a plane.
I don’t think there’s much connection between a plane’s ability to do a sideslip and how well it glides. A sideslip is just what naturally happens if you apply opposite aileron and rudder inputs. I think the issue is just that it’s a rather acrobatic maneuver to perform in a large passenger jet.
Yes an airliner is not designed for it and could easily get into a deadly spin when doing it. Especially engines out because you have two huge surfaces blocking airflow. A glider can do it pretty naturally because of its extremely low stall speed.
Since a sideslip increses air resistance by essentially flying sideways, if I didn't know that it has been done, I'd say it might even break apart a (long, thin) plane that wasn't designed for it. And it still might, but at much higher speeds than close to landing.
It's not unheard of for airliners to use a sideslip when landing in a crosswind, so I don't think structural strength is likely to be an issue at landing speeds.
