Will constructive adhesive adhere to a smooth epoxy surface? If you want to use constructive adhesive, I would rough up the epoxy surface with some sand paper first. Don't sand down to the metal surface, otherwise you may get some rust on the metal. Personally - I would use some sort of mechanical fastener in addition to the constructive adhesive.
Just a couple of thoughts on how you can attach everything.
1. Lets assume you have a face frame that the door attach to. You can attach the face frame to the metal stand buy using screws. Just drill a hole with a counter since bit. Then drill the screw into the face frame. I would put silicone (or waterproof caulking) where the screw is going to create a water tight area. Then plug up the hole with some hole plugs. I personally would use a contrasting color plug to create a decorative look. Assuming your face frame is oak - I'd would use purple heart for a nice contrast.
2. Another option is to actually attached the face frame to each other. Then at the corner, use some wood to create a brace that wraps around the metal frame. Screw the wood brace to the frame on the inside. Then cover the hole with some silicone to prevent the screw from rusting.
3. Depending on the size and weight of the face frame and door, you can always consider using some strong rare earth magnet to attach the face frame to the metal frame. Just find a bunch of magnet. Sink the magnet into the wood face frame. Attach the magnet to the wood using some sort of adhesive. The magnet will allow the face frame to attach to the metal frame. One advantage here is that you can always take of the face frame for full access.
There are other ways you can do it. If there were more pictures, we might be able to suggest other ways of doing it. If you need help, I'd wouldn't mind coming over and helping. I just can't do it until I am finish with my own house projects that are incomplete (finishing the wood floor, finish the electrical subpanel in my garage, drywall the garage, and build my woodshop).
Minh