Here's how I do it.
First off, .308 Win cases are cheap enough that it doesn't pay to anneal them.
If you reload rare, very expensive or wildcat cases, then annealing may be called for.
I anneal my .223 cases when forming 7mm TCU. Especially when using hard military brass.
I use an electric cordless drill, the case holder from a Lee trimmer, a 650F Tempilstik, a Bernz-O-Matic torch and a bucket of cold water.
You'll have to experiment a little on where you mark the cases with the Tempstik. I mark the .223 cases that I form 7mm TCU right at the mid portion of the shoulder.
I adjust the flame and turn the drill on at fairly low RPM aiming the flame at the center of the neck.
When the Tempstik melts, I immediately quench the case (while still held in the drill) in the cold water. This stops the annealing process.
Don