The Dane has been enlisted by a series of clubs including the Premier League side in an effort to improve their restarts.
Gronnemark is also working with FC Midtjylland, AC Horens, an unnamed Bundesliga club and two other sides.
A world record holder for the longest throw-in, the 43-year-old has already seen a marked improvement from the Reds, with Gomez and Andy Robertson central to that.
And Gronnemark has also seen a significant improvement in Scotland international Robertson's technique on the left side.
"I'm very proud that he [Gomez] assisted an important goal with a throw-in during the Nations League game between England and Croatia," he told Goal. "His throw-ins belong to the best in the world.
"When I started working at Liverpool some media had laugh about me but after the England game everybody praises me. Even journalists from the U.S. and Argentine wanted to talk to me.
"[Robertson] started with throw-ins of only 19-20 meters which is quite short for a fullback. It's very dangerous to throw that short as a fullback because there is always pressure for the teammate who gets the ball.
"But he improved a lot and is able to throw about 27 metres now, which is a great improvement. He is very smart and has much more options now. I'm very proud of him."
After a six-month probationary period, Liverpool have seen it fit to give Gronnemark a contract until the end of the season.
Manager Jurgen Klopp admitted after his arrival that he had never heard of a throw-in coach but has welcome the impact of the master thrower.
The German admitted he had no hesitation in recruiting Gronnemark upon meeting him and the coach has spoken of his first encounter with the former Borussia Dortmund boss.
"I was in the car and when Klopp first called me I've missed it," he added. "After hearing Jurgen on my voicemail, I was shocked. He invited me to a meeting in Melwood.
"After the meeting, he was thrilled and wanted to work with me. Since June, I work as a coach for Liverpool and I am living my dream.
"I love the work with Klopp and the team. It's fantastic. Jurgen is a great leader and the whole team is very helpful. The working atmosphere is awesome."
Gronnemark has also been pleased results Liverpool have had on the pitch since he's started working with them.
"It's great to hear that someone like Jurgen is praising me during press conferences. Before I was joining his staff, he thought the Liverpool throw-ins were good but after meeting me he was convinced that he has to hire me.
"This season we can keep more than 75 per cent of the balls after throw-ins. Last season the quota was at about 50 per cent. A great improvement."