Defeat would have all but ended their hopes of matching last season's semi-final showing given that it would have left them at least 13 points shy of the final play off place with just seven regular games remaining but McCusker is convinced that a remarkable comeback is now on the cards.
"We're aiming for the top four and hoping to go one better than we did last season," said McCusker. "We didn't do ourselves justice at the start of the season and we're having to make up for that now. Hopefully we haven't left it too late.
"We felt hard done by when we went to Musgrave Park so we were keen to avenge that and show the league that we can win these kind of games.
"We're on a bit of a roll. It's great for us to keep momentum going and keep pressure on the teams above us …we are able to keep our sights firmly on the top and keep moving forward.
"When your back's against the wall in any walk of life you come out swinging. We have to play the rest of the season as if our lives depended on it - that's what it will take to get us in to the top four."
While most of the PRO12 teams are all set to enjoy two weekends off now, the Scarlets will be back in action a week on Friday when they travel to Belfast for their re-arranged clash with fellow play off contenders Ulster.
The original fixture was postponed due to adverse weather conditions last month and the new match up now has arguably even more resting on it given that the Scarlets have won both games in the weeks that have followed.
Victory at Ravenhill will be hard to come by seeing as Ulster haven't lost there since the opening day of the campaign and were beaten just once at the venue in the league last season but assistant coach Mark Jones insists morale will be high ahead of the trip across the Irish Sea thanks to the nature of last week's win.
"That was a very good performance: we defended heroically in the second half and our set piece held up. We prepared in the week for a challenging encounter and it was exactly that," said Jones.
"There was a lot of technical stuff in there which was working particularly well but I thought there was an appetite there that they weren't prepared to give up the try line. That's no mean feat against a side like Munster.
"We haven't set ourselves any targets other than winning the next game, that's the position we've put ourselves in. We've given ourselves a chance to put some pressure on the teams above us. We want to finish as high as we can and we want to be the best that we can."