Using metaphors in coaching is considered an "advanced coaching skill", yet the implementation could not be easier. It does require a certain amount of imagination on coach's side but I personally believe that all of us have that side inside us; the trick is to be able to bring it out.
Similarly to the "Meta-View" method, using metaphors is helpful in situations when client's analytical mind does not allow them to open up to new ideas and unexplored territories. It is especially suited when helping clients to step out of their comfort zone.
How exactly does it work? When stumbling upon a mental block, we can simply ask clients: "How does this situation feel like" or "Where do you feel this stress in your body? Describe the feeling". Yes, a metaphor brings the clients to that "feeling place" but in a subtle and gentle way. Usually clients' answer to questions like these immediately involves some sort of metaphor. The job of the coach is then to maintain that "being in a different, creative place" and keep the client in it for as long as possible or needed.
Once clients manage to "bridge" the reality with the feeling or the creative image of it, they can work through the original issue/problem more easily. Let's say the client "walks through a thick, dark forest", you can ask him: "What do you need to do to get through that forest"? "How much longer do you need to walk before you see the clearance"? What does the clearance represent to you? How does it feel once you have made it through the forest"? etc.
Working with metaphors takes clients to a world of fantasy for a while and there, seemingly, everything is possible. When clients accept that feeling and carry it over to their real life, the coach has done her/his job well and clients have got more clarity on how to move towards their goals.