Export your object. Edit the obj file and add the prefix "sweethome3d_window_mirror_" to every g line you want to appear as chrome. Usually you can see the material in the following line that starts with "usemtl". That makes finding the correct g lines to change easier.
You can change the color to make it look like silver, bronze, etc.
Example: "g shelf_1_1" > "g sweethome3d_window_mirror_shelf_1_1"

Import your object and when you render a photo the parts with the prefix will look like chrome (not in the 2D or 3D panes).

You can see an example of the result here: http://www.sweethome3d.com/support/foru ... ,200#62953