As you probably know if you’re on this page, Logitech wisely decided to not support any of their old racing wheels on PS4, only their new G29. If you have a G25, G27 or DFGT, you’re out of luck.
The answer, the big “screw you!” to Logitech, is GIMX. You just need to make a USB adapter and run the GIMX emulator on your PC or Raspberry Pi.
I’ve spent way too much time in the past couple of months setting up my G27 wheel on my PS4, including running GIMX on a Raspberry Pi to take the laptop out of the loop. I decided this was way too much hassle for most people to go through, and I could make up a bunch of adapters relatively easily (yeah, right). So here’s my “hello world” website where you can finally buy this adapter!
Note that you can pay directly with a credit card through the PayPal link even if you don’t have a PayPal account.
I will not have time for support questions, so please read the GIMX wiki and forums for help. Hopefully soon I will also post Rpi images to get you off the ground quicker with Rpi, and I’ll probably also sell the little circuit board with a power button and status LED as described here, because it’s quite handy.
Enjoy your old wheel on your PS4!
[UPDATE]
Power button and status LED now available: http://www.steve-marton.com/gimx/?p=99
Full plug n play rpi package now available: http://www.steve-marton.com/gimx/?p=101