The Reds, who also displayed new first team coach Cristian Damiano, were understandably delighted to have landed the quartet.
"We have brought in four players, I am as excited as I have ever been by a group of pre-season signings, these are four players of the highest quality," said Liverpool chief executive Rick Parry.
"Commitment is a value we put before everything else, they have come to win trophies and develop their careers - and they have come because of Gerard.
"It gives me a lot of pleasure to introduce these five new faces, all of whom will play an important part and play a significant part in the future."
Kewell was the biggest name of the new faces and Houllier could hardly hide his delight.
"When I came here I was always a great admirer of his. When they [Leeds] were in the Champions League I watched him in action a lot," said Houllier, "and I am very happy to have brought him to the club.
"He will play an important part in our game, and I know our fans were looking for us get him - he should settle into the team well and he is a typical Liverpool player - I am happy the board allowed me to sign him.
"I was determined to get him here and I was pleased that he was determined to come here, to play with the likes of Michael Owen and Steven Gerrard.
"It says a lot about his desire and commitment - it is fantastic and gives a boost to the fans and the squad because of his influence.
"He had one year left, we were clever - if a player wants to leave you should sell him before then.
"You want a player to be a winner and a fighter, and we have picked the right man, he will bring maybe the missing link which sometimes we have, he can score and create - he is not going to play in a defensive position.
"In modern football you need to be able to do everything - look at Thierry Henry in the Confederations Cup - we took Harry for his creative skill and for his ability to be a team player.
"I can tell you we are proud to have all these five players."
The Australian was pleased to have finally penned his long awaited deal, and opined: "I am very pleased to be here.
"I could have had Champions League football elsewhere, but I want to achieve things here and think big things will happen here and I want to be a part of that."
Kewell was more than happy to pay tribute to the Leeds fans.
"I have always said Leeds have been perfect, they have supported me for nine years, I have nothing against the fans and I hope they have nothing against me," he said.
"I am sorry to say they never put numbers in front of me and that did in a way disappoint me and you expect a bit more friendship."
Also unveiled was right back Steve Finnan, who arrived from Fulham earlier in the summer.
"He [Finnan] was recommended to us by Karl Heniz Riedle, we have monitored his progress and have watched him since," revealed Houllier.
"He is a proven Republic of Ireland international, he is a good player - a modern full back who likes to go forward without neglecting the defensive duties. We have looked at him for some time and are happy to get him.
"We are normally successful when we have an Irish player," quipped the Frenchman.
"We had to fight hard to get him here and we were clever and anticipated the move. He had already made his mind up before anyone else could move for him."
Finnan himself added: "I would like to continue the tradition as part of this club.
"Hopefully I can be successful. First impressions mean a lot and when you get shown around, there is nothing more you want."
Also on show were French starlets Sinama-Pongolle and Le Tallec, who spent last season on loan at Le Havre after agreeing a deal in 2001.
"They are both young and in fact we spotted them two years ago," said Houllier.
"Fortunately Rick and I signed them before they won things."
Speaking through Houllier, Le Tallec added: "It is very strange, I am young and coming to a club like this is a major experience - but now I have to train with the likes of Owen and Gerrard."
Also using his manager, Sinama-Pongolle commented: "We are aware that we have a lot of progression to make, but it is a great club to be at and learn at."
Finally, Houllier revealed his new first team coach Damiano.
"He has come here as first team coach to work alongside Sammy Lee," he added.
"I have known Cristian for a long time and he was assistant of Jean Tigana at Fulham last season - he is a football man and knows a lot about the game.
"We worked in France together and he is first class."
