The premise is that in one's imagination anything is possible. You can make things be any which way you feel like, you can make anything happen, whether it "makes sense" or not. It is not something serious, it is a playful activity.
At the same time, work with the imagination is most effective if the person realizes the creative power of imagination. It is not JUST the imagination. She should be brought out of any belief that it is ONLY some hallucinations of the mind that have nothing to do with anything. She doesn't need to have heavy duty beliefs about how her imagination creates the whole world either, as long as she doesn't have overly limiting beliefs about her ability to create.
Just generally exercising visualization in a certain area is beneficial. Trying out different scenarios will open up more options. It is particularly freeing to try out a lot of things that are considered impossible in the outside world. It is a good idea to make things disobey natural laws and do all kinds of funny and ridiculous stuff.
You can do that without any particular plan or method, just steering the client with your own imagination and intuition, however staying within the area we are working on. Like, if the subject in question is work, you can have her imagine a lot of things she wouldn't normally do at work, particularly the one's violating the reality of her limitations. Have her tell the boss off and offer him a stick of dynamite as a cigar and after he exploded, scrape the pieces off the ceiling and ship them to Nicaragua to use to patch pot holes. Then create him again, this time with a big red nose and antlers. Send him out to direct traffic, give everybody in the office a 10000% pay raise and assign them personal slaves. The more ridiculous and funny, the better.
Concentrate on anything that is an inability, anything the person has a hard time even imagining. If she has trouble talking to others, exercise the ability in imagination, very thoroughly, gradually making it more and more challenging. Have her first talk to a very small person who is looking the other way and who is tied to a chair. Then have her talk to more and more people, under more and more challenging conditions. Have her talk over the PA system to a stadium full of angry people carrying automatic weapons. Always focus on expanding her ability to do it. When she is hesitant, work over the area particularly carefully in many different ways. Make sure that it is fun and playful, not hard and intimidating.
The more precise detail one can imagine, the better. Have generalities specified. If visualizing "a car" find out what brand of car it is, what color it is, what equipment is in it, how is its condition, who is inside, what is in the glove box, etc. It is the details that make realities real. The only reason for the physical world to appear more real than an imagined world is the amount of specific perceptual details. If you can make as detailed a visualization it becomes reality.
Use all perceptual systems. Make sounds, feelings, smells, and taste in addition to pictures. Create a full reality, with lots of detail.
When exercising visualization abilities, change things often. Blow things up or throw them away and make some new ones. Don't get attached to anything, just vaporize it and make something else, even more detailed and interesting.
You can add visualization to any module. You can use it particularly when some limitations are apparent in a certain area, or you can just generally work over the area.
Visualization is also excellent for setting a positive direction. It is a very useful thing to do at the end of a session. Have the client visualize how she would like things to be. For this purpose we want the visualization to be as real and convincing and stable as possible. But again, with as many perceptions as possible, and as much detail as possible. Be aware though, that if it is a future direction, it must be attractive. It usually works well to leave a bit of mystery about it. If one knew everything about it, there wouldn't much reason to go out and work for it. So, it should be very real and attractive, but at the same time it should be apparent that one doesn't have it YET.