The 23-year-old right-back currently plays for NK Domzale but had a trial stint with Wanderers last week.
Ilic told the Slovenian press: "I was in England for three days and had some medical tests. I trained with the first team and played a game for the reserves.
"I also met Sam Allardyce and watched the Chelsea game. I'm thrilled and I hope this transfer will go through."
Meanwhile, according to reports Everton striker James Beattie is a target for Wanderers manager Sam Allardyce in the January transfer window.