It is possible to make such map, actually.
Though, you will need custom models (the portal) and surely a good bunch of new textures, too. You could devide the map into two halfs. One resembling the underground army base and the other one maybe the inside of a pyramid, like in that first movie. Both connected by the portal...
The major flaw about this, however, would be exactly this one-way limitation. I guess it would work better with
Sauerbraten (cube2), since it provides portal enteties, which would allow for multiple portals.
In case, you don't mind differing from the original story you cold also have one room (army base) in the center with 4 portals on each side leading to 4 different locations, which may also be connected by portals. At least, this way you will provide a better gameplay.
However, this will be quite a lot of work for a map, which will not meet AC's style and you should be fairly skilled at mapping in order to make it look somewhat believable, regarding the engine's limitations.