If drawing at Celtic Park in the sides' original William Hill Scottish Cup fourth-round tie was a remarkable achievement for Arbroath, the Irn-Bru Second Division side will tomorrow night be hoping to knock out Neil Lennon's side in the replay.
There is no tactical template for causing upsets against superior opposition – defend for your lives and hope for a break or two is about the size of it – but Sheerin has plenty of personal experience that will guide him and his team of part-timers.
One comes from Celtic themselves, the Arbroath player-manager studying their Champions League victory over Barcelona to see if he could pick up any tips on how to prosper in the face of unrelenting pressure.
Sheerin, still playing regularly at 38 years old, will also draw upon a coaching seminar he attended with Alex McLeish, the former Rangers manager, and ex-Celtic midfielder Peter Grant, when the pair recounted how their Birmingham City side upset the odds to beat Arsenal in last year's Carling Cup final.
"We did kind of look at that game [against Barcelona] and think that it's something we will have to do against them," said Sheerin. "But you need the players to be spot on on the day, and they all were in the first game. Hopefully we can be as disciplined as we were that day and, if we get a bit of luck, then who knows.
"I did my A [coaching] licence recently and Alex McLeish and Peter Grant did a seminar. The timing of it worked quite well because the draw came out not too long after it and it was something I went back to.
"So I got a couple of wee bits from that as well, and you pick up whatever you can. With our budget against their budget you have to balance it out as much as you can."
The Old Firm connection does not end there. In January, Arbroath hosted Rangers in the same competition and lost 4-0. Sheerin wonders if he was too adventurous that day and has vowed to take a different approach in tomorrow night's tie.
"I think I've learned from that game," he said. "I was a little bit naive last season because I thought we could get at them with a 4-4-2 formation. But there was a realisation that once you do that you're leaving yourself open to concede and, against the quality they had on that day, we certainly suffered.
"I think you have to [be more cautious]. When you're playing against the quality Celtic have, you have to do that. We'll try to be a bit more cautious and a bit more disciplined than we normally would be in the league, that's for sure."
Tomorrow's replay is being broadcast live on Sky Sports which, combined with a share of the gate receipts from both matches, will secure the Angus club a funding windfall.
"The financial implications for us are huge," added Sheerin. "To have both sides of the Old Firm in a calendar year is massive for the club. The Rangers game helped the club as we were in a bit of debt but we managed to clear that and purchase new pitch covers, which is obviously helping for the game to be on on Wednesday.
"Now the Sky money, after the gate not being great at Celtic Park, is another massive help.
"They'll be able to run the club well for two or three years from the money they've earned from this game."
Celtic have won twice since drawing with Arbroath in the first match – beating Spartak Moscow to reach the last 16 of the Champions League, then winning 3-1 at Kilmarnock – but Sheerin is not without hope.
"We rode our luck a wee bit at their place, which I think you have to do to get a result. But if my players can perform to the same sort of levels they did at Celtic Park, then I don't see why we can't acquit ourselves well."