You need to get access to the rear of the fog light switch.
6th gen instructions....
Remove the coin holder tray.
There are two screws where the coin holder sits... remove them
The little dash panel should come loose and can be taken out easily
giving you access to the rear of the switch
Rough Image
7th gen instructions....
if shonnv or anyone attemps this with a 7th gen, please post back with your instructions and i can put them all together
Rough image to remove lower cover for switch access?
You should see 5 wires coming from the fog light switch connection.
Cut the BLUE wire behind the switch (leave some slack at the switch side)
Splice into the RED/BLACK wire (dont cut it, strip some insulation off)
Strip and Attach the BLUE wire(switch side) to the RED/BLACK wire.
Use electrical tape or whatever to seal the connections. Dont forget to cover the open BLUE wire
Reassemble.
How it Works...
The blue wire recieves power from Red/Green which trips the relay to turn on the lights.
Red/Green is hot whenever your headlights are on.
Red/Black is hot whenever your headlights OR parking lites are on.
Cutting the blue wire on the switch and attaching it to Red/Black will let you run the lights with the parking lights or headlights.... (and will also bypass the relay that turns them off when your Highs are on)
Note: I will not be responsibe for your f*ck ups.
This info had been compiled from various sources
I havent done this mod on my car, since i do not have fogs,
but this has worked for others, and it should work for you