The Manchester United centre-forward was believed to be close to joining the Championship outfit on a loan basis earlier this season, but a foot injury halted the switch.
However, Coyle has revealed that the majority of a deal has been agreed for the 20-year-old to sign on at the DW Stadium on a temporary arrangement.
"I would be very surprised if that is not concluded in the next day. I spoke again with David Moyes yesterday just before they were flying off to Germany. The paperwork and everything has just to be signed. We're confident that will certainly happen," he told reporters.
Keane has made one senior appearances for the Red Devils.