Muggleton was part of the Wallabies' coaching team for 10 years. He helped them to World Cup glory over France at the Millennium Stadium in 1999 and to victory over the British & Irish Lions in Australiad during 2001.
The deaf squad spent the morning working on fitness before being put through their paces on the outdoor training pitch.
Team manager Geraint John said, "We are grateful to John, Team Manager Garan Evans and the Scarlets for welcoming us to their impressive new facilities and giving their time to spend with our squad."
He continued; "It was interesting to see the techniques used at this high level of rugby and I'm sure the players will have learned a great deal from the experience."