You can do it, but it won't be easy...

I don't recall if the DRLs are as bright as the headlights in GPs.... That may be something to keep in mind.

Basically you would just have to rewire it so that instead of running power from the DRL relay to the headlights, you would reroute it to the fogs. If the way I said that makes sense...

For my silverado I am running all my lights when I hit my highs using resistors across the bulb relays in the fuse box. Personally, I think heads and fogs for DRLs on a GP would be better than just one or the other.