As always, in order to use this mod you will require DSFix. Link: http://www.nexusmods.com/darksouls/mods/19/?

Step 1: Git DSFix ya spoon.
Step 2: Enable texture override. This is achieved by editing DSFix.ini and changing enableTextureOverride to 1.
Step 3: Locate tex_override folder. Usually found at: Dark Souls Prepare to Die Edition\DATA\dsfix\tex_override.
Step 4: Dump contents of Blue Flame into tex_override.
Step 5: ???
Step 6: Profit.

Conglaturations. You have now modded your Dark Souls game.