In other words, to gain an entry point to re-experiencing we would start with something unwanted in the present. If it is not experienced now, or it isn't unwanted, we won't need to do re-experiencing on it.
The best entry point is an unwanted physical feeling. That is, something that the person can feel right now in her body. There are several reasons for that.
First of all, kinesthetics are more sticky than for example visual or auditory perceptics. Kinesthetics have a lower frequency and are much more difficult to localize in time and space. Most people can quite easily change around pictures they make in their minds. They can move them around, make them bigger and smaller and so forth. Feelings more easily generalize into ALL space and time.
Rarely will a person voice any complaints about pictures being stuck in her mind. Mostly what she will have trouble with will be feelings that she can't change. Feelings are quite tightly linked up with one's action and behavior. To do anything different in one's life, one has to FEEL like doing it differently. No amount of thinking or visualization makes you do anything different unless you feel like doing it different.
Also, feelings are fairly tangible. One can verify them by what the person actually feels in the body. It is hard to run away from a pain in one's stomach and it is likely to stay there until we actually have cleared it. That makes it much more difficult to cheat. If we were dealing with just pictures or words, it would be much easier for the person to fool herself into thinking we were done when we weren't.
A distinction should be made between feeling feelings and thinking about feelings. There needs to be some actual perceptions that the person can describe. If she says that she is "hopeless" we would want to know what that means to her in terms of perceptions. How does she know that she is "hopeless" - is it in her stomach, in her head, is it an empty feeling, a heavy weight, a buzzing sensation, or what is it? The words themselves are not good enough, we need actual, tangible perceptions that are there right now. That usually means some sensation in the physical body, but not necessarily. "I feel hard walls around me", "my space is mushy" would also be quite valid.
Smell and taste are also useful in defining the unwanted feeling. They are actually the least distorted senses.
Usually we would want some kind of a verbal description of the unwanted feeling. However, that is only to make it easy to refer to it. It should mainly be identified to the person as the exact perceptions in it. She needs to be able to feel it now, and she needs to be able to recognize it again.
Getting the feeling can be as simple as asking:
"Do you have any unwanted feelings or reactions?"
You might also notice when she is talking about something else that we are dealing with a feeling that is unwanted.
She might identify it satisfactorily right away, such as: "A buzzing pain moving down my right arm". If she doesn't, we will ask for some more specifics.
To clarify what the feeling is, it is useful to be fluent in kinesthetic qualities, like: weight, temperature, hard/soft, vibration, resistance, friction, solidity, viscosity, etc. Many people will have a hard time identifying what a feeling consists of and will need some help on it. Some people will even insist that the feeling has no identifiable qualities except for that it is "depressed". You need to be able to handle that smoothly and get it identified further anyway.
Instead of just asking for unwanted feelings out of the blue, we could use a more organized approach to find them. We could interview the person about various aspects of her life: family, work, health, hobbies, accidents, losses, etc. We would notice which areas appear to have unwanted feelings in them, or which areas that are generally loaded. Chances are that if it is an area the person is concerned about or has a lot of attention on that we would find unwanted feelings in it. After the interview is done, we could then systematically go through all those areas and ask for more specific unwanted feelings within each one, until each is clean.
We could also start out with prepared lists of classes of feelings and ask if there are any specific unwanted feeling in each of those classes. E.g. we could ask for pains, discomforts, pressures, tightnesses, etc. We could also ask for more abstract feelings and emotions, e.g. fear, anger, grief, depression, hopelessness, frustration, as long as we make sure that the words are linked up to something that can be perceived and recognized.
We could also start out with a list of body parts, or with a list of things most people have in their lives, and try to locate unwanted feelings in each of those areas.