Ellen- first off I am sorry it has taken me so long to reply, you are raising important questions - I will give them a stab and Lynn will join in as soon as she can.
I am sure that you are correct in that depression, anger, grief and/or shame related to some event in their lives, taxes your patient's coping abilities. I do believe that smoking is a drug addition and one that is responsible for more deaths than any other. This is going to make your job much harder as the body has to fight on a physical as well as psychological level. The exploration of what was going on prior to a relapse must be helpful. You will be trying to teach your patients how to anticipate situations of increased risk for them to relapse. The 12 step models might even turn out to be very useful in treating smokers! The one suggestion I have since your time is sooo short, is to add a focus on guilt as a potential precipitant. All the other affects you have mentioned are important as well and helpful but they are probably more intuitive and if they were the problem you might have seen more successes. I don't know, but if I had only one session I would treat it as a crisis intervention and very boldly try to enter into their unconscious process in order to see if they were ruining their life out of quilt toward a loved one, or a belief that the deserved to be punished or others would prefer them dead. It could also be an identification or compliance to a loved one. That person could be alive or dead, a smoker or someone who also put their health at risk in another way (drug/alcohol/aids). It could be occurring because they felt they had achieved a better life than a sibling or parent and the patient felt that to put their health at risk would even the score. The possibilities are endless but the idea would be to look for a reason that your patient would feel so compelled as to continue to do something that they know will kill them.
They are acting suicidal so I would treat them as I would a patient who was acting self-destructively. With regard to the occurrence of severe negative affect that precipitated you patient's return to smoking, I would look to see-(by asking them) if the event triggered a need to hurt themselves-or feel worthless etc. I would also want to see if their had been a previous event or trauma that caused a resurgence of quilt feelings that set off the chain of negative affects and smoking. All this in one session- of course not but I would be interested to see if a questioning of possible quilt motives would help in some of your cases. What do you or others (chime right in! ) think?