So how did this pan out? Were you able to improve your mental imagery? What methods did you use? :)

When I was a kid I tried the Relaxation Response for a month and it improved my very weak ability for a time. But then I stopped doing it! Perhaps the act of taking 10-15 minutes a day to focus on my 'mantra', which was just a picture of "one" written out, helped. It was great because after the month I was able to, for the first time ever, recall pages from my textbook, almost like I had the beginnings of a photographic memory. I'm thinking of trying this again.