I make a chocolate version for myself. Carnation has changed their formula recently, and the product now gives less product, less protein and slightly fewer calories than when I worked the numbers. However, the following is still close. I do it by grams, so I used the USDA nutrient database to convert to teaspoons.

For straight chocolate, 1 serving

Mix:
7 tsp. cocoa (6 grams)
4 tsp. sugar (17 grams)
8 tsp instant skim milk powder (17 grams)

For mocha, I would use the same sugar and skim milk powder, and start with 50/50 cocoa and coffee by weight, which would be 3-1/2 tsp cocoa and 2 tsp instant coffee, then adjust to match the taste you're after.

I prefer mine with the chill off, so I nuke the milk for a few seconds first, which helps the cocoa dissolve (with vigourous stirring). Sifting the cocoa into the milk helps a lot. If you make it in bulk, use a blender to reduce the particle size of all the ingredients, and it will blend more easily into cold milk.

Lori