I regret I do my steaks on a Treager, not a WSM. Here is my method, perhaps this will help you:
I sear the steak, either by cranking up the Traeger to 450*+ or by heating a cast iron pan to as hot as possible searing for around 30 sec or so. I then go to "smoke" mode and leave steak in for 1 to 2 hours. On the Treager this is around 150-160. I then switch to 300* and bring it to my desired temp (140*).
I bet you could do this by searing in the pan and then smoking in the WSM at 225-250 with desired wood chunks. I am not sure how long till the magic number you like your steak at will be hit. I am sure the gurus here like Kevin Taylor, Chris, and the MM master Jim Minion have done a few steaks on a WSM. GOOD LUCK!