Alex has been visiting family in Tasmania, therefore is already acclimatised to Australian conditions.
Edinburgh back-row forward Stuart McInally has also been added to the touring party.
Scotland head coach Andy Robinson explained: “We’ve called up Stuart as a precaution given a hand injury that John Barclay sustained in training yesterday. John should be available for selection for the Test but we felt it better to ensure we have sufficient back-row options.
“Alex will meet up with the squad tomorrow. We’ve gone for him as we are still liaising with the IRB, French Federation and Castres Olympique to have Max Evans join us as soon as possible.”
Castres Olympique are involved in the Top 14 semi-finals this weekend with the IRB’s June Test window, which is covered off in their international player release regulations, beginning next weekend.