Run the app as usual, but click EXTRACT as soon as it has loaded
Extract everything, open oggchan.exe and be welcomed by wonderful pinku. Browse to your source image, then NEXT.
Click Add audio file, then simply select one or more soundfiles. Change the tags by clicking them and typing something.
Clicking NEXT again, you may pick where to save the image. You may also pick the level of quality; lower numbers equals smaller files. Also, select whether you want to recompress ogg files or the source image (to save space).
Now you just hit DONE and wait for it to do its magic. When finished, all tags are on your clipboard for your convenience. If you want to embed more stuff into another image, click NEW.