This might work but is untested, so beware.
You could use $ionicSlideBoxDelegate.next(); twice or even more to get to a chosen slide.
If you create a method that executes when clicking an item in de slidemenu with a parameter of the destination slide index, you could use that value and the value of the currentIndex to calculate how many times you have to execute $ionicSlideBoxDelegate.next();.
Is this clear enough?