I did that on a Challenger 13 years ago. This was done when I was doing a complete restoration on my car. I cleaned out the leaves and stuff that drips out of the rockers and sprayed some runny paint in the quarter so it would flow down and out and cover the inner part of the quarter to help preserve it incase any moisture got in there. I took and welded the ends of the channel so the water couldnt drip out on the lower quarters. Then I used Por-15 and lined the channel to cover some pin holes that were in the bottom of the channel. I took 2 small pipe nipples and drilled holes in the bottom of the channel about a foot from each end and welded the nipples in the bottom flush with the channel. Then I drilled a hole in the top of the wheel well and ran some hose to the nipple and thru the top of the wheel well so the water would drip onto the top of the tires.