I think this is the best option. You can download practically anything from a torrent website. The torrent program that most people seem to prefer is uTorrent. Once you download the torrent program, you can then partake in downloading torrent files. There are tons of websites out there that host thousands of torrent files. I have a few popular ones listed here. Simply put "psx final fantasy tactics" or "ps1 final fantasy tactics" into the search and that should take you to its download. Or to save you some trouble, here are direct links to Final Fantasy Tactics torrents:
• Final Fantasy Tactics (NTSC) - 194 MB
*If any of the above are in .7z or .rar format, use 7-Zip (it's free) to extract them.
Final Fantasy Tactics is a large download. It could take several days to download it. You'll need to leave your computer on overnight.
You can play Final Fantasy Tactics right on your computer with a Playstation (PS1) emulator. I have the best ones for download in my emulators page. And if you need assistance with the Playstation emulator, check out my emulation help site, Video Game Emulation for Newbies, for help.