1. You need latest DSfix installed
2. In DSfix.ini set enableTextureOverride value to 1
3. Put PNG file in " dark souls folderdsfixtex_override"
4. IMPORTANT! PC version of DS have two different sets of buttons for switching in menus and ingame (when picking up items etc.). There is no way for me to make both sets work at the same time, so you will need to change keys so they match "Ins"/"Del" switching in menus. Sorry, cant do anything about this.