The Saints conceded to Niall McGinn in the 15th minute at Ibrox before a second-half Stevie May double rescued the Perth club and sent them into their first-ever cup final.
"When I was there that was my aim - to get to the club to their first cup final," Duberry told skysports.com.
"Now every one of those players have written their names into the St Johnstone history books as the first set of players to get to a cup final.
"It's a massive achievement and, fair play to them, everything they get from this point on they deserve.
"I've played in a semi-final for the club myself when we lost to Motherwell 3-0 (in 2011). It was heartbreaking, it was horrible, but these lads have overcome that hurdle which has been over the club's head for so long now.
"To get to the club's first ever cup final in what I think is the first full season that this management team have had is amazing.
"They showed tremendous character (to come back from behind) and words just cannot explain what they have done and how big an achievement this is for the club."
"I'm going to look at my diary and hopefully try and free the date up so I can get there and be a part of it myself."
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