Steele (elbow) threw a bullpen session off the mound at Petco Park on Monday, John Fanta of NBC Sports reports.
It remains to be seen if Steele, who has spent the season recovering from UCL revision surgery and a flexor strain, will be added to the roster for Chicago's wild-card series against the Padres. If he is added to the roster prior to Tuesday's Game 1, he would presumably be deployed out of the bullpen.