With two games remaining in the regular season, at home to top-six rivals Workington Town and Oldham, Hunslet are fourth in the table and could still finish as high as second.
It has been an inconsistent season for the Parksiders, but Thornton feels they are running into good form at the right time to mount a promotion challenge.
They had to dig deep to snatch a 34-30 win at London Skolars - their fourth victory from the last five games - and he believes that sort of close, intense contest was valuable practice for the do-or-die fixtures coming up.
In a see-sawing encounter, Hunslet looked to be heading for an agonising defeat when - with the scores level - Skolars set for a drop goal in the final seconds.
But that was charged down, Hunslet went the length of the field on the counter-attack and Gareth Potts squeezed over at the corner to win it.
“That’s three [wins] on the bounce now so we are building a bit of momentum going into the play-offs,” Thornton said.
“We showed a lot of spirit and togetherness.
“We didn’t have an easy journey, it took us seven hours to get down there so we were basically straight off the bus and on to the pitch.
“That wasn’t ideal preparation and it is never easy to win down there, so to come from behind twice - 16-6 and 30-24 - was really pleasing.”
Injuries and suspensions robbed Hunslet of several first-choice players and overcoming adversity added to Thornton’s satisfaction.
“The players who came in did a good job,” he said.
“It wasn’t the prettiest, but three or four weeks ago we might have crumbled.
“The last few weeks have been different, we have got a togetherness that you want when you are planning for the play-offs.”
Hunslet - whose squad remained in London after Friday’s game to watch the Coral Challenge Cup final - picked up one significant injury.
Thornton said: “Adam Robinson got a bad knock to a leg.
“We will check on him over the next few days, but Jon-Luke Kirby is back this week.”