Cut the marzipan roll in half lengthwise, then cut each half into 12 equal pieces and shape each piece into an oval. Pinch the small end to make the nose and eyes.
To make the ears, working with 1 mouse at a time, wet 1 end of 2 almond slices and stick them into the marzipan above the eyes.
Line a baking sheet with wax paper. In a small bowl, microwave the chocolate chips at high power, stirring every 20 seconds, until smooth, about 1 minute.
Insert a toothpick into the wide end of each of 12 mice. Working with 1 at a time, dip the mice into the chocolate, tapping the toothpick on the side of the bowl to remove any excess. Transfer to the prepared pan and refrigerate until firm, about 15 minutes.
Meanwhile, using a toothpick, make a hole in the wide end of each white mouse; insert the licorice tails and place the eyes. Remove the toothpicks from the chocolate mice, then insert the licorice tails. Serve at room temperature.