Steele will begin a rehab assignment with Triple-A Iowa on Wednesday, Taylor McGregor of Marquee Sports Network reports.
Steele has managed to successfully toss several bullpen sessions, proving that he's ready to progress to facing live hitters. He'll presumably need to make at least a few appearances in the minors before being activated from the 60-day injured list, at which point he would likely provide support for the Cubs out of the bullpen considering he won't have enough time to build back up to a starter's workload.