The PCW brings its video signals out to the expansion port, and I've seen various projects that use that to have the PCW display on an external monitor. The PCW technical documentation also says that it's possible to do it the other way round -- OUT 248,8 to stop the PCW outputting video, and then let an external source drive the video signals. I think this was probably used in the Swift-286-PCW, but has anyone else experimented with this?
Could be risky, if you start driving the video pins without disabling the CRTC ( or if pcw resets and it gets enabled again) I would worry about the gate array getting damaged. Maybe I'm just being paranoid.