Hi Vikram,
Unfortunately there isn't any programs that I'm aware of that can do what is necessary to create a good bootskin. In fact, my tutorial was for photoshop only, because Paint Shop Pro (PSP) doesn't give you the control over the way the image is converted to 4 bits. So bootskins created with PSP or the built in converter in Skin Studio look pretty bad.
As far as the progress bar goes, it is just a 22 pixel wide by 9 pixel high bmp image. The critical thing is that it must share the exact same 4 bit color palette as the main bootskin image. Otherwise you will get a bootsking that flashes all sorts of different colors, and in most cases locks up the computer before it even gets booted up. The only way to get out of the error, is to start windows in safe mode, and change the bootskin to one that you know works.
Sorry for the bad news.