"Vern made contact over the New Year to say they were looking for an attack coach with the Scotland team," O'Halloran told Fairfax. "I went over for a few days in February to check it out.
"I didn't foresee I would get an opportunity with an international side so it's a pretty good opportunity."
The Blues' coaching saga has once again highlighted the dearth of coaching options in this country.
Warren Gatland (Wales), Joe Schmidt (Ireland) and Cotter are all overseas, as is Robbie Deans (Panasonic in Japan).
Former Counties coach Milton Haig has taken Georgia ahead of Italy in the world rankings and sparked rumblings that the eastern European nation is ready to join the Six Nations.
Former All Blacks flanker Jono Gibbes has carved out a name for himself, firstly with Leinster and now with Clermont, and Chiefs assistant Tom Coventry is joining London Irish after this Super Rugby campaign.