If this is accurate, it means Okung can (not will, but can by rule) return to practice in six weeks and be on the roster in eight weeks.
If Okung goes on the IR with the return designation, and he is placed there this week, he should be eligible to return for the Nov. 17 game vs. the Minnesota Vikings.
Here's an explanation of short-term injury reserve, a spot the Seahawks have not used yet:
Starting in 2012, the NFL and the NFLPA reached an agreement allowing one player placed on injured reserve to be brought back to the active roster. Provided that the player was on the final 53-man preseason roster (A rule exempted for the 2012 season), and that the injury is deemed to keep this player unable to practice or play football for an estimated six weeks, the player may be allowed to practice after Week 6, and be activated to play after Week 8.