Ok, lemme try again.
Where the "BM" or "Bitmap" or "Image" Coodinates come from:
You have created a custom image. The actual position of the "map" portion of that image is selected entirely by you. Because of that, the leftmost, rightmost, topmost, and bottomost sections of the map are variable. You need to use an image editor to determine the these.
I use Adobe Photoshop. As you can see from the image below, I pull down a "Guide" line until it just touches the topmost portion of the map. I can tell from Photoshop's cursor position display that it is exactly 5 Pixels from the top of the image.
Now I can pull a guide over to the leftmost portion of the image. That is 9 pixels from the left side of the image.
I use the same process to get the rightmost and bottommost coordiantes. See those in my image as "Image coordinates."
Where the /loc Coordinates come from:
When you ran around the map, spamming /loc, you created a big log of in-game coordinates. My Mapper2 tool, and other's various tools, scan through those coordinates and determine what the largest and smallest X and Y coordinates are. These are the furthest extents of the in-game coordinates for the map. We know that: The largest X is the leftmost, Smallest is Rightmost. Smallest Y (Mathmatically) is Topmost, Largest is bottomost.
Now we've got all the data to plug into Tony's tool.
The mistake I made last time was forgetting that ZoneRec is in the format -W, N, -E, S -- I got the W and E's signs reversed.
Hope that explains it better.