In a food processor or blender, crush pretzel twists until crumbs form.
Add sugar; pulse until combined.
Add margarine and mix well.
With machine running, add 2 tablespoons of the limeade concentrate, processing until well mixed.
Place mixture in an ungreased 9-inch pie plate.
With back of spoon, press mixture firmly into bottom and up sides of pan to form pie shell.
Bake at 375°F until set, about 5 minutes. Place in freezer for 10 minutes to cool.
Meanwhile, in a clean food processor or electric mixer, combine ice cream, remaining limeade concentrate, tequila and liqueur; process or mix until just blended. Spoon into cooled pie shell and sprinkle with lime zest. Freeze for 2 hours before cutting into 8 slices.