They visit Workington Town in the League 1 play-off final tomorrow with the last place in the Championship in 2022 at stake.
Doncaster, who finished fifth, have had to battle hard to get to this point, winning three successive elimination games against Hunslet and at North Wales Crusaders and Keighley Cougars.
Their hosts – led by Horne’s former Hull FC half-back partner Chris Thorman – finished second behind promoted Barrow Raiders and are favourites to progress.
However, the South Yorkshire club have beaten them both times they have met this season and Horne said: “I think the groundwork for Sunday has been put in throughout the year.
“Now the challenge is getting the lads recharged and energised heading into the final. We’ve fallen short the past couple of years but we’ve given ourselves a great opportunity to win promotion.
“It’s a really tough test though against a good Workington side who got a similar result against Keighley as we did.
“But I’m looking forward to it. I think the key is staying calm and relaxed and just making sure everybody knows their role within the team.”
Doncaster came from behind to snatch a dramatic last-minute win at Keighley.
Horne insisted: “For us to come back after the first 20 minutes last week and win was great.
“But we’d be kidding ourselves if we thought we could start as badly on Sunday and get away with it. For us the play-offs are different; it’s like a Challenge Cup game at the top level – you play it differently.
“There will be two teams giving it their all and desperate to be a part of the club’s history.”
Doncaster will go away from their normal routine by travelling up to Cumbria today in readiness for the contest.
“Some lads like being in their own beds the night before a game but we felt it was better for the group to spend time together and prepare right,” explained Horne.
“We want to eliminate travel on the day and reduce the stress of sitting on a bus in traffic. Hopefully we can go one better now and get that promotion as that is what we targeted from day one.”