Have you actually got that to work jv-map? Because i can't get skyportal (with or without a skyorigin) to do anything except act like caulk.
I think the problem with the portal_camera/portal_surface is that we don't have a portal surface to project the image on. I tried the portalsky and common portal textures, but they don't work. Do you think we could write a shader with "surfaceparm portal"--maybe using one of the reflection textures?
I tried everthing I could think of and can't get it to work. Also it makes my LOD terrain act funny (change shape) as I move around the map. It may be because I had the skyorigin in a small sky box below the ground. I tried to make a portal surface shader for the portal camera/surface and that didn't work either.