Patches Steam (1.4.1 or whatever) to 1.0 Can be anywhere on your comp as long as the Patches folder and Borderlands1Patcher.exe are together. (Patches and Borderlands1Patcher.exe need in the same folder)

Fill the Textbox in the exe with your steam BL1 install (C:\Program Files (x86)\Steam\steamapps\common\Borderlands) etc directory (double clicking on the text-box brings up a folder explorer like BL2 patcher) Click Patch Wait until the thing is patched It will backup your old BL1 options/saves and force 1.0 to create a new options so you don't crash