Club record £125m signing Isak has been ruled out since December, having fractured his leg and had ankle surgery.
The 26-year-old Sweden striker managed 16 appearances and scored three goals for the Reds before his injury against Tottenham.
"I think Alex is in a really good place because Sweden qualified for the World Cup and, apart from that, he's going to train with the group again for the first time tomorrow," Slot told the club's website.
"If you've worked so hard for three, four months or something like that and then to return to team training, that's for everyone very nice. So Alex is, in that sense, in a good place."
Liverpool are preparing to face Manchester City in the quarter-finals of the FA Cup at Etihad Stadium on Saturday (12:45 BST).
The Reds signed Isak from Newcastle United for a British record transfer fee in September.
He had surgery on an ankle injury that included a fibula fracture, sustained following a challenge by Micky van de Ven as he scored against Spurs in a 2-1 win on 20 December.
