Tollett, a Great Britain tourist in 1996, joined Quins last October, but could return to fill the problem stand-off position at Huddersfield.
Luke Goodwin is Cup-tied, Glen Air has not yet staked a convincing claim to the position and the Broncos used their back-row forward, Peter Gill, there against Hull KR in the last round.
The London chief executive, Tony Rea, was in negotiations with Tollett and Harlequins last night and a Broncos spokesman said: "We are pretty confident."
The Leeds prop Barrie McDermott is to appear at a disciplinary hearing tomorrow, hoping to avoid a suspension that would rule him out of the Super League season after being sent off in a friendly at York last Friday.
A delegation from the Australian Rugby League, including its former director- general, Ken Arthurson, is flying into Britain this weekend to fight through the courts for pounds 400,000 it claims still to be owed from the World Cup here in 1995.Reuse content