Apart from what I said in the other thread, I was given a piece of information from a psycho at Attwood's:
She said that on average, 15 minutes of attention is about all that someone with AS should be expected to give to something that they aren't obsessed over. She said that a 30 minute break to do what you want to, and then another 15 minutes of your attention on the subject you aren't obsessed over, seems to help many. So it'd go, 15, 30, 15, 30, and etcetera, rather than trying to do it all in one sitting.
I don't know if it works, but it does make sense, as you have a reward for doing the 15 minutes of boredom.
If 5 minutes is all you can give, it'd go 5, 30, 5, 30 and etcetera. It'll probably take awhile, but since it's upsetting you so much, it might be worth giving it a try.
I have nothing else, sorry.