Instead of just using the image we created in step 2, I found this tool to be quite useful in constructing plans for my mosaic as well as giving me a piece count.
Bricksaic and be found at: http://www.bong69.com/site/pages/bricksaic.php
Although Bob Kojima has made a fantastic tool, and you really can do everything in Step 2 in Bricksaic, I was having some issues making it do exactly what I wanted. As such, I did all my tweaking in Photoshop and used Bricksaic only as the "roadmap" tool.
We're going to setup Bricksaic to interpret our image exactly as it is. Once we have all the settings as we like, we'll then click "Make Map" and the resultant images can be printed off and used to create our mosaic.
*The first image is of the normal Bricksaic screen. To some, the screen will be intuitive, to others, it won't be. Essentially, you'll want to follow the buttons marked 1, 2, and 3. The rest of the screen is the options for those buttons. If the screen is too daunting, just follow the image notes on the image below :)
*The second image is of the options dialog that pops up when you click "Make Map." Again, it's pretty self explainitory.
*The next 6 images are the different plates that are created. On the bottom of each image you'll find the number of 1x1 bricks needed for each color on that plate.
*The Final image is the total peice counts for the project. This is quite possibly the most useful aspect of this tool as it clues you in on what you need to order.
In order to keep the fidelity of these images, I've uploaded them full size. As such, I recommend clicking the "i" in the top left corner of the image and downloading the original image to view.