My automatic writing was done on a Hermes 3000 typewriter, but any other tool can be used. Computer, pen and ink, crayons, etc. Whatever it takes to get the exercise going is what you should use.
What is writing? Words on paper, nothing more. So long as you are putting words on paper - or here, into cyberspace - you are writing.
Rather than focus on content - what every blocked writer does - instead devise an automated way to write. Then do it.
In my case, with the Hermes, the task was to set my typewriter single-space with margins full out. Then, beginning at the top of the page I TYPED WITHOUT THINKING until the page flew out of the machine. Here's one example:
LANCE'S AUTOMATIC WRITING: "You And 39 Others"
http://randomfilm.com/poems/39others.gif
Again, the idea is to eliminate thought while you write, and instead reach a certain mechanical goal for the exercise. For me it was one solid page of words, NO STOPPING until the paper came out of the machine.
If you don't use a typewriter but are on a computer, you might set a timer for the exercise, say 10 - 15 minutes total. Likewise with pen and paper.
Now here's the hard part. You have to do the exercise every writing day for an extended period of time: it was three years for me, then I was done.
(Cont'd)