Kidney, who this season has guided Munster to their fourth Heineken final and will be hoping they win their second European title, says farewell to the club in order to take up the head coach's job with Ireland.
Losing finalists in 2000 and 2002, before securing the trophy in 2006 with a victory over Biarritz at the Millennium Stadium, Munster hope to rip up the form book and defeat the French giants at a venue once again expected to be draped in red.
Kidney is due to take charge of Ireland when they return from their two-Test tour of New Zealand next month, replacing Eddie O'Sullivan, who resigned following a disappointing Six Nations and World Cup.
Kidney was in charge when Munster went down 9-8 to Northampton in their first appearance in the final, and also two years later when a Neil Back hand prevented them securing a late win over Leicester.
However, they made it third time lucky against Biarritz and Wallace (pictured) hopes they can repeat the feat against Toulouse at the same venue.
"I am sure most people would agree that we are going in as the underdogs and, if our support is anything like we had at our last final two years ago, we can do with that help," Wallace told the Irish Independent.
"That first final defeat was very, very disappointing because, not only was it so close, but we also felt we had not performed as well as we knew we could and should have played.
"In our second final we were beaten by a better team on the day when Leicester won 15-9 in Cardiff and we went into final number three knowing that three Heineken Cup final losses would be simply too much to bear.
"Now we have the opportunity to even up the balance sheet and it would be great if we can make it two from four.
"Last time Declan left us back in 2002 it was on a losing note so it would be brilliant for him to go with a win this time. He has led us to all the finals and it would be great to give him another trophy."
Wallace concedes that the Irish province will start as underdogs and claims they will have to be at the very top of their game if they are to cause an upset.
"Toulouse are a great side and a huge challenge - we will have to play out of our skins to beat them. They epitomise all the best things of French rugby," added the Ireland flanker.
"Regardless of who plays, they have a potent back three and a great pack of forwards. They are strong across the park but their back row, along with lock and captain Fabien Pelous, are at the heart of their side.
"However, their main strength is their fantastic squad depth which, to put it mildly, is simply mind-boggling."