Alright this is what you're going to do. Get a male speaker connector, or go to the junkyard and get this option plug connector from the door of an Integra that has power door locks, looks like this:
I want to say it's on the passenger front door only, but I don't remember 100%. These can also be found on Civics.
Now stick that option plug into the empty parking light option output on your under-dash fuse box between the two yellow plugs in this picture:
This will give you 12volts when the parking lights are on. Connect that to your relay assuming that your relay is wired as negative switched. You should be using an "auto" SPST or SPDT relay.
The parking light output should go to 86, 85 should be grounded, or vice versa. 87 should be connected to your battery with an inline fuse. 30 should be connected to your fog light power input.
Use a grommet where the wire passes through the firewall. Do not let wire rest against a metal edge. Use electric tape and split loom to protect your wires in the engine bay. If at some point in the distant future, your parking lights are stuck on all the time, it's because your option plug wire is grounded.