The on-loan Newcastle defender had returned to his parent club from his first temporary spell with the Buddies on the day Danny Lennon's side knocked Celtic out of the Scottish Communities League Cup semi-final.
However, having secured a second loan deal until the end of the season, he is desperate to get his chance to play a part in humbling Neil Lennon's side again.
Celtic's manager joked before the draw was made that he'd like to see St Mirren come out the hat in order he could get his revenge, but he wasn't the only one jumping for joy when the Scottish Cup draw was made.
"I knew St Mirren had a massive cup-tie against Celtic and I really didn't want to miss it, so I arranged to come up to Glasgow for the semi-final," Paul explained.
"I had my suit on and was just about to leave the house when I got a phone call from Newcastle telling me to get into training.
"I was not best pleased but I caught the match on TV and was jumping up and down like a fan. I was willing them to score every time they got near the box. Getting to the final is a tremendous feat."
The 21-year-old believes the spell he has had with Saints has helped to improve him as a player.
The Paisley side have been on something of a roll, with three victories in three competitions last week.
It is back to the grind tomorrow with a long journey north to Aberdeen and Dummett is keen to play his part.
"There was a lot of talk about me returning to Paisley during the transfer window, but Newcastle had a lot of injuries and I was told to stay put in England," he said.
"I made my United debut in the FA Cup at Brighton and that was a dream come true. I was buzzing.
"Now I'm back at St Mirren but Graham Carey has been playing at left-back – and playing very well – so I don't expect to walk straight back into the team.
"Naturally, I'm here to play football but I know I will have to fight for my place. I'm really looking forward to it."
Meanwhile, ticket prices for the final are £25 and £20, with under 16s paying £10.