Open your finished 2560x512 image. Make sure that your background layer is transparent. Go up to Layers, Merge, Merge Visible.
Go up to View, click on Toolbars and then click on Web. This will give you a new web toolbar. On the new toolbar, click on the Image Slicer (shaped like a stop sign cut into 4 quarters). A new window will open and this will be the Image Slicer.
In the Image Slicer window under the Format listing choose the PNG option. Click on the Optimize Cell button and then choose the Transparency tab. Choose Alpha Channel Transparency and Existing Image or Layer Transparency. Click ok. Tick the box for Apply Optimization to Whole Image.
In the Image Slicer window under the Tools heading click on the Tic-Tac-Toe image. There's a big box up top of the Image Slicer that has your image inside of it. Click your mouse once on the image and another smaller window will open. This is the Grid Size box. You want 0 Rows and 5 Columns. Click on Ok. You're almost done!
Click on Save As. Name it index.htm (this assumes you've already created an empty folder to place the images). Your images are in the folder, and you can delete the index file.
You will need the image converter located here on WoWI. Drop the exe file into the folder where your sliced images are located. Now (with your mouse) drag one png file at a time over the top of the BLP2PNG.exe file and it will convert it to a blp file. Do that with your remaining png files and you're done converting your images