Once you have the Winning Eleven 6 PS1 ROM, you need an emulator. Here is the best setup for every platform.
Unlike modern 50GB monsters, the WE6 PS1 ROM is surprisingly small. Winning Eleven 6 Ps1 Rom
The raw Japanese ROM is intimidating if you don't read Kanji. Here is the standard patching workflow. Once you have the Winning Eleven 6 PS1