"It is a nice buzz and he looks a lovely horse the way he won last Saturday over there," says Bosson.
"He can run on the speed and has the draw to get there so it is a real bonus, although, to be honest, I don't know exactly how it came about.
"Firstly they contacted Aidan [Rodley] my manager and then Mark Guest, who has been booking me some rides over there. I am just happy to be on."
Bosson has ridden occasionally for Waterhouse before.
"I rode a horse for her way back when I was a teenager and also a few more when she had a lot more to do with Te Akau."
Volcanic Rock, who races in the China Horse Club colours, has won two of his four career starts but is rated a $21 chance in the richest juvenile race of the carnival.
Bosson has also picked up a big-name ride for Chris Waller on Saturday in Funstar, a mare who he knows well as he beat her riding Probabeel in the Group 1 Surround Stakes at Randwick last year.
Funstar races in the A$200,000 Dane Ripper which also features Taranaki mare Coventina Bay, who makes her Australian debut in the 1300m event with regular rider Samantha Collett in the saddle.
Coventina Bay hasn't raced since pushing Avantage close when second equal in the Group 1 NZ Breeders at Te Rapa on April 17 but was brilliant winning a strong 1200m trial on the Sunshine Coast last week. That caught the attention of plenty as she has opened the $7 second-favourite with Australian bookmakers in what is a lead-up to her main winter aim, the A$600,000 Tatts Tiara on June 26.
While Saturday's meeting is traditionally known as Stradbroke Day because of the A$1.5m Group 1 sprint feature, this year that might be put in the shade a touch by the new A$1.2m race The Q22, a 2200m weight-for-age race.
It could be the centre of attention as it features Doomben Cup sensation Zaaki, the early favourite for the Cox Plate and a budding weight-for-age star in Australia.
He is $1.50 to win again in the hands of James McDonald in a race where Bosson will ride Cambridge-trained ATC Derby winner Quick Thinker.