I have the Mindfulness book too - it is good. Again with a CD - you do only have to lie there and let it wash over you. I am a book nut though - so if I have a problem I buy a book! (My tendency is procrastination if I don't keep a clear head.)
Try an ipad hypnosis app which all he has to do is to listen to. I don't think it will just magically lift (I wish it would though obviously!) but if all he has to do is listen ...... I collapsed with exhaustion after a long period of stress (slept for a week - seriously I was awake about 3 hours a day) and felt so ill everything felt rather hopeless. Anyway an 'energy / waking up refreshed' app worked for me and helped bring me round.
Also if you have lots of things going round your mind, then maybe he isn't sleeping too well either (or has a crap quality of sleep ifyswim), and his body clock is probably all stuffed up. So maybe a hypnosis track to sleep well at night might also help?
How about what he is eating - oily fish is good for depression and there are other foods - maybe that could be a 'task' for the day - sit and eat something which is nutrious together. Daylight is also good. So are funny films - if you make yourself behave as if you aren't depressed, then the mind will catch up apparently.
My mother gets depressed, and it isn't fun to see - but for her she lashes out and uses depression as an excuse. She hasn't changed in my lifetime, but that is because she blames external factors, rather than changing the way she sees the world. CBT can be lightbulb moment like, but I can't get her there. You really have my sympathy - probably why I came back on this thread.
And like the others have said - please don't forget YOU. It can be rather contagious living with someone who suffers.