Jerome scored a cracking long-range effort at Anfield while Benitez added a second from close range - his first for the club.
McLeish believes the goals will have given them a massive confidence boost and that they will improve the more they lead the line.
"They've been a handful but I think there's more to come from them," he told the club's official website.
"They obviously gave themselves a big shot in the arm the other night by scoring a goal each - their first of the season.
"Although they're paid to score goals, that's got to have done their confidence the world of good.
"Cameron is looking very hot in training and long may he keep that confidence.
"But he also needs to keep working at the technical side of his game."
McLeish concedes Benitez will benefit from opening his account in England, although he still has a lot to learn about the culture of play.
However, the Scottish manager has been pleased with his application to date and hopes he continues to learning and develop.
"Chucho has made us better in the front areas and he's another one who will thrive on goals," he continued.
"He is still young and he's a bit of a superstar in his own country but he's come into the Premier League now which is the league where all the players in the world like to play and he's still developing in this league.
"But he has been a handful for defenders and if he keeps listening and learning and adds a little bit of the South American culture to the English one he can become a very good player.
"I've been impressed by both of the front two, not only the way they've played and given defences problems, but for their work rate as well which has been great."