Having spent a frustrating four years in international eligibility limbo, Fijian-born Speight says he will become a "Wallabies sponge" next month when he joins the Australian squad in camp to fast-track his Test dreams.

Speight was shocked when McKenzie called and invited him to join the Test camp for 10 days next month, despite not being eligible to play for Australia until September 11.

The move is designed to speed up Speight's transition to international rugby and help him make an immediate impact when his drawn-out eligibility saga is over. Speight has been waiting almost four years to be eligible to play for Australia.

''Going for the Wallabies jumper was the ultimate goal for me and now I believe it's within reach," Speight said.

''I'm just going to go into the Wallabies and soak everything up, pretty much be a Wallabies sponge and absorb everything.

''It's an honour for my family and all those who support me [back in Fiji], they're my motivation and that makes it extra special.''

Speight is one of four train-on players added to the Wallabies squad to give them experience of a Test-match environment.

He won't play in the Tests against France, instead having to bide his time until he qualifies as an Australian in four months.

IRB eligibility rules state that players not born in Australia must live in the country for three years before being considered for Test selection. Speight moved to Canberra at the end of 2010. But a brief playing stint in New Zealand in 2011 pushed his Wallabies eligibility back until September.

He will be available for the Wallabies' clash against Argentina in Perth on September 13.

Rather than view the invitation to Wallabies camp as a tease, Speight said it was a "blessing".

"I've waited a long time for this, it doesn't bother me waiting that little bit longer," Speight said.

"It was very tough to handle last year when they told me I wouldn't be allowed to play for Australia for another 12 months.

"But now I know it's good to be close rather than not being considered at all. There's just a bit of extra satisfaction because I went an extra mile."

Speight signed a new two-year deal with the Brumbies this week. He's also the only player who hasn't made his Test debut to get an ARU top-up contract. It's an indication of how highly he is valued in McKenzie's plans for the World Cup next year.

Speight initially thought McKenzie was calling him to discuss his new deal with the Brumbies and ARU.

He was on his way to the Regina Mundi Church in Soweto, an historic meeting place in South Africa's history with bullet holes in the walls from the apartheid era, when McKenzie called.

"I knew I wasn't available for the June Tests so I didn't expect anything. So when Ewen called, I just thought it was about contracts," Speight said.

"I was in the middle of Soweto, one of the tough places in South African history and I got some very good news, I was just so happy."

Speight was on a day trip with teammate Tevita Kuridrani, visiting Nelson Mandela's former home, social rights activist's Desmond Tutu's house and historic venues around the town.

"It was an eye-opener," Speight said. "Nelson Mandela's home was no bigger than people's garages back in Australia.

''There's a lot of history in Soweto. We saw the slums, the shacks and people living in a tin box with no water or electricity. Our last stop was the Mandela house.

''It was a grounding experience after everything that happened with the Wallabies. It just makes you realise how lucky you are, there are people worse off than you so you don't take anything for granted."