The o-ring slid on to the MAF with very slight resistance. It sat well in the airbox opening, but not quite as snug as I would have liked (that extra half a mm thickness would have been good). The MAF seemed to slide into the airbox opening snugly with the o-ring installed. Jammed the rubber plug into the SAS elbow and used some of the handyman's secret weapon to keep it secured. Didn't have any liquid adhesive/sealant on hand that I felt would adhere rubber to plastic well under high temps. Dropped in a new Mann filter, and my S70 is now running on its stock airbox again.
For peace of mind, I want to leak test it. Thinking I'll have someone hold the throttle at a high RPM while I smoke around the SAS elbow and MAF opening, and see if any smoke is getting sucked in. Still going to look for a slightly bigger o-ring, but I think this will work for now.
On a side note, my TCV has lost its home on the front of the main fuses box. There isn't enough room for it here with the airbox installed. Will have to find a new place to mount it.
