I tried this 20 years ago, slippage always nailed me in testing. Also tried other indexes including dow and 10year T-Note to generate signal on ES, the Dow was closest to generate a profit, gave up after 6 months. Perhaps though now, perhaps software can create cash charts that are a percentage of the full index that are a second or two faster than ES. Just too much work for a tick.
I still don't understand why this person want to use a Index chart when the futures chart is available