If so, should you wrap the chicken completely in foil, or leave the bottom open so the steam can get in?
Don't wrap the chicken in foil. Instead you can use a steamer basket inserted in a pot with the lid on (making sure your liquid does not touch the chicken) and steam it that way.
If you don't have a steamer basket and what you are trying to do is replace one, instead of wrapping the chicken roll that foil into balls or strips and use it to elevate the chicken above the cooking liquid in your pot.
If you wrap in foil, the chicken will be cooking via the heat transfer from the foil rather than from the steam.
You can add all sorts of seasoning to the chicken while steaming it if you wrap it up nicely. This is the reason for using tin foil. :)