That's a high dosage. Here's an alternative to the Ashton method that might be easier for you:
The easiest way to taper Xanax or any other benzo
I've done Xanax w/d after over a year of 1mg per night for sleep. I believe doctors who prescribe benzos longterm for sleep are totally irresponsible, because they stop working for that purpose. Attending AA also helped for the support I got. However, due to intractable insomnia, I got on Seroquel, which really helped right away. Unfortunately, that caused worse sleep issues, so I wouldn't recommend going that route. Although, you could try the above method and use Seroquel short term to overcome the worst of the sleep issues. Just don't stay on it for more than a month.
The other thing you could do is just plain go to rehab, where they will take you down rapidly. I feel if I had done that, I would have benefited tremendously.
So, if you're serious about getting off benzos, I would consider the above info. If you can handle the sleeplessness piece, you may get over them for good. I can't handle the sleeplessness piece, so I may be stuck with them for good. Just my .02 cents.