Well, here it is!
Step 1: Tools and materials
ink jet printer (continuous ink supply system not required but recommended!)
paper cutter (recommended)
spray mount or spray adhesive (optional)
weather proofing spray (optional)
Step 2: Find a map
If you haven't noticed already, on google maps you can click the tiny little arrow on the left side bar and it will disappear giving you a larger map area to work with.
I wanted this map to flow intuitively from one page to the next. To get that effect, you need a long (wide) and narrow (short) map.
I chose to make a map of my home area, Silicon Valley, which is sort of a landscape rectangle (see photo).
Take a screen shot and then paste it into your photo software.
Step 3: Tricky part
Then carefully select the upper half of the image (6" by 20"). (I wish Paint Shop Pro had a way to tell it specific coordinates for selection, but it doesn't, oh well)
Once you have the upper half of the image selected, you need to rotate it 180 degrees.
Now save your image and print it out to your printer.
In my case, I had to print the image out on poster setting 2x1 (printed over two pages in landscape mode).