Centre-back Mirfin, 26, left the club following relegation in the summer to join Championship side Watford on a Bosman transfer.
But his time at Vicarage Road has only brought five first-team appearances, and he is keen to return to North Lincolnshire on loan to play regular football.
The Hornets have prevented him from leaving earlier in the transfer window as they want to keep him as backup, and any move could hinge on the future of Adrian Mariappa.
Watford have rejected an approach from Wigan for Mariappa, and should he leave the club it could end any hopes Mirfin has of doing likewise.
Midfielder O'Connor is out-of-contract in the summer, and the club would need to sell now to guarantee a transfer fee.
BBC Humberside said on Tuesday morning that the Iron's board of directors were considering the bid.
The player himself has said he does not want to leave the club.
"I'm not leaving..I'm not goin 2 leave with the position we are in," he tweeted on Monday evening.
The Iron are also continuing to look at trialists Eugene Bopp and Ronnie Gibbons.