1. Download the Steam version of Grand Theft Auto San Andreas.
  2. Disable autoupdate (Right click on San Andreas on Steam > Properties > Updates).
  3. Locate your San Andreas folder is (Right click on San Andreas on Steam > Properties > Local files > Browse local files...)
  4. Download GTA_downgrader.
  5. Copy all files from "\GTA_downgrader\GTASA_downgrade_patch" to your San Andreas folder, launch "install.bat" now wait, when everything will be done its will close automatically.
  6. Install San Andreas Multiplayer to your San Andreas folder.
  7. Launch SA-MP and play!