Alexis is due to face his former club on Saturday.
Slot said: "He's a player I would play in all three positions in the midfield because he is so comfortable in all three.
"I saw a lot of him at Brighton because there was a manager I was quite interested in back then (Roberto de Zerbi).
"He is now at the moment the midfielder who plays a bit in between. Ryan (Gravenberch) is almost always the deepest. Dom (Szoboszlai) or Curtis (Jones) are playing a bit higher and then Alexis is in between.
"It depends on how dominant we are whether he is the second 10 or the second six. He is comfortable in both phases of the game. He can help us bring the ball out from the back and he is also capable of making the difference in and around the 18-yard box. We want to see him in both situations as much as we can."
On facing Brighton again after their midweek Carabao Cup win, Slot continued: "In football we are used to playing the same team after a few days. Both teams didn't start with the same team they will start with on Saturday.
"I think with both managers it is a positive thing because you know a little bit more about the opponent.
"The way we filled in the number nine position was interesting because I thought it worked really well. In the end I prefer to play with a real number nine but it is not a possibility if we have injuries. It was good to score three goals without playing with an old-fashioned number nine."
On Brighton manager Fabian Hurzeler, he said: "Some people need the 20 years of experience to get to this level. Some other talents have it. He is one of them. For him, experience is probably not such a big thing. Usually it is good to have some experience but there are exceptions to the rule."