In a medium bowl, beat cream cheese, rum, powdered sugar, cinnamon and nutmeg with an electric mixer until smooth. Set aside.
In a microwave safe bowl at 50% power, melt 1/3 cup of white chocolate and Egg Nog for 30 seconds. Stir until completely melted. Add melted chocolate/egg nog into the cream cheese mixture and blend thoroughly. Place in freezer for 15 minutes for easier handling.
Line a cookie sheet with parchment paper.
To make truffles, Roll dough into 1 inch balls and place on baking sheet. (Note: roll quickly, dough will become sticky when handled). Refrigerate for 15 minutes to harden.
Melt remaining white chocolate in microwave, again on 50% power, stirring until smooth.
Using a spoon, dip each truffle into chocolate, covering completely. Return truffles to prepared sheet, and top with colorful sprinkles immediately.
Refrigerate truffles about 30 minutes, or until firm and chocolate is set.
Store in an air tight container for up to 1 week.