OBSE works out of the box for retail copies of Oblivion but not for Steam version on Linux. Here are the simple steps to make OBSE to work in Steam

  1. Install Oblivion
  2. Install OBSE
  3. Open the terminal and enter the following commands. Replace /path/to/Oblivion/directory/ with the Oblivion folder.

cd "/path/to/Oblivion/directory/"
printf '\x90\x90\x90' | dd conv=notrunc of=obse_loader.exe bs=1 seek=$((0x14cb)) 
printf 'obse_loader\x00' | dd conv=notrunc of=OblivionLauncher.exe bs=1 seek=$((0x1347c))