The forward has been on the periphery of things at Pompey this season.
Having arrived at the Blues from National League side Bromley in May, Dennis is still to feature in the third tier.
His two appearances haveÂ been in the Checkatrade Trophy, while he's made just six match-day squads in total.
Dennis has been behind the likes of Gareth Evans and Joe Mason in the pecking order during Pompey's League One title charge.
Nevertheless, the 26-year-old impressed on his Fratton Park debut in the 3-2 win over Tottenham under-21s last week.
He won the free-kick which led toÂ Evans' goal and was awarded man of the match.
Jackett was pleased to see Dennis pick up his accolade against Spurs.
He'll now be targeting his League One bowÂ '“ and must take his opportunity if it arises.
'˜I was pleased for Louis,' said Jackett.
'˜The ball flowed through him very well and you could see that his technique on the ball was very good.
'˜I think he is a very natural number 10. The ball flows through him and his release of pass is good.
'˜His weight and timing is something that means a move can flow through him.
'˜That's a very pleasing aspect of his play.
'˜It's hard to play just odd games, as you would always want to have a run of games.
'˜When you come into the side in cup games, I liken it to the first game you play in pre-season.
'˜You look a bit rusty, there's not much pattern and you're hard to judge in the first game.
'˜You can then start to judge in the second or third game when you start seeing a little bit of pattern '“ that's how it is.
'˜When you haven't played for a while, it's quite a hard thing to come out of nowhere and play.
'˜He now has to keep his head down, keep working hard and be ready when his chance and opportunity comes.'
Pompey's impressive form this campaign has made it difficult for Jackett to accommodate Dennis in his side.
Evans has been superb in his new number-10 role, netting six times before the trip to Scunthorpe.
Wolves loanee Mason has scored goals in the Championship during his career, while Andre Green (Aston Villa) and David Wheeler (QPR) are both on temporary deals from second-tier clubs.
Dennis isn't the only Blues player to be out of favour this season.
Fans' favourite Danny Rose has made just a solitary League One appearance, while the likes of Christian Burgess and Brett Pitman have feature nowhere near as much as they'd have liked.
Regardless, Jackett has told those on the fringesÂ to continue preparingÂ for a potential Pompey chance.
The manager added: '˜We've had a settled and reasonably successful side, limiting Louis'Â chances so far.
'˜That's limited his chances, as it has other people.
'˜The big thing is being ready when you do get your chance and called upon.
'˜As disappointing as is it if you haven't played, my message would always be to make sure you're ready because when you do get your chance you have to take it.'