They secured their spot in the two-legged showpiece after seeing off derby rivals Yorkshire Carnegie in Sunday’s semi-final.
Doncaster had never even reached the play-offs before this campaign but, after a highest-ever finish of second, are now just one step away from the Premiership.
Table-topping Bristol, of course, are experienced campaigners at this time of the year having reached the final for a third successive season – although they have infamously crumbled against London Welsh and Worcester Warriors previously.
Given the vast amount of money invested in a star-studded squad since relegation in 2009, there is huge pressure on head coach Andy Robinson, their former England chief, to now deliver a return to the elite.
They will be favourites but Cusack told The Yorkshire Post: “Yes, we are in uncharted waters and we don’t know what to expect.
“We’ve a few boys who have played in Championship play-off games before but as a club this is our first time there and we’re the ones breaking new ground.
“So, let’s keep it going while we can. We’ve been doing great stuff for the last eight months so let’s keep going and keep being Doncaster Knights and no one else.”
Clive Griffiths’ side have good reason to show confidence; they won at Bristol in November, the only side apart from Bedford on the opening day to do so this campaign, and only lost to them in the home fixture after an injury-time score.
Having been playing in the largely part-time National One just two years ago it is no surprise unfancied Knights are now being likened to football’s new Premier League champions Leicester City after their own rags to riches tale.
Irishman Cusack, who has expertly piloted the side during his first season since joining from Plymouth Albion, said: “It is good to dream but you can only dream if you put in the hard work and we’ve put in a lot of that.
“We work really hard early in the week on opposition teams and getting ourselves right and then come the weekend we’re ready to go and are a match for any team. I’m counting down the days to this final; they will be two massive games and two crackers I can’t wait for.”
Doncaster host Bristol in a week’s time before making the return trip on Wednesday, May 25. Cusack, 28, is set to face British Lion Gavin Henson, the famous Welsh fly-half. But the former Munster player insisted: “It doesn’t matter who we’re up against.
“It could be anyone. If we work hard as a team and keep being Doncaster Knights we’ll be a match for anyone. It’s a great bunch of lads and then you’ve got Clive whose enthusiasm for the game is beyond anyone I’ve ever worked with.
“That filters down into the playing squad and breeds an air of confidence. We put the hard work in, and when we go out on the field on a Saturday it shows.”
Doncaster’s defensive resilience and work ethic was evident against Carnegie.Granted, they lost the second leg 17-14 but, such was their appetite for graft, they saved a raft of potential tries that could have seen their advantage overhauled.
“That performance shows the commitment,” added Cusack.