Blackwell, 53 has been without a managers job since his departure from Bramall Lane in August 2010, but since then has been coaching in America and is scheduled to go to Burkina Faso this summer.
He has been approached over the weekend through an intermediary about taking over the vacant managerial role at the KC Stadium.
Tigers owners; Assem and Ehab Allam have been impressed by his record whist with Leeds, Luton and the Blades - having guided both the Blades and the Elland Road club to the Championship Ply-Off Final (2006 & 2009) and their owners believe he could be the man to take them back into the Premier League.