[Accelo]

I am assuming you didn't mean "using a toggle switch to turn the overdrive on and off". But the lock up feature of the torque converter.
Others have given you some options for wiring.
Doing nothing is another option. It will just work like the early transmissions.
Highway RPM will be a nominal 200 rpm higher.
I ran a 4L60 like this for years behind a BBC in my 1971 C20.
Some believe they will overheat when ran this way.
Mine had a transmission temp gauge and I never had this issue.
It would not go over 100mph in overdrive, it would shift back to third at 100mph.
I had zero transmission issues.
I like to see lock-ups working but it's not required.

One issue when using a switch method is it will extend your emergency stopping distance.
It's the equivalent of stopping, with a manual transmission, a leaving it in gear with the clutch out.