As far as I know, there's no :unlock statement. Doors in Adventuron aren't the nicest doors in the adventure world, as they're one-way doors and you can only have one per room. Although there's a bit of coding involved, I find it easier to just do your own doors, then you're in full control.
If you can, can you take a look at the first three locations in The Witch's Apprentice? There's an unlocked gate between the first and second location and a locked door between the second and third location. The doors can be opened and closed from both sides. The locked door is unlocked by pressing the button on the intercom. It sounds like this is the sort of thing you need.
If this suits your requirements, I can send you some source code.