Basic Sweet Cream Recipe (see earlier post)
+2 TBSP extra sugar
+5-6 tsp cold-brewed coffee concentrate (or more to taste)
Add the extra sugar at the same time as the other sugar and the coffee at the same time as the milk and cream.
This recipe makes for a very subtle coffee flavor - it reminds me of Stony Field Farm's Decaf Coffee ice cream. You could make a concentrate using traditional hot brewing, but I think the cold-brew flavor is better for ice cream and iced drinks.
Here's my recipe for coffee concentrate, adapted from here:
Put a rounded 1/3 cup of coffee grounds (apparently fine grind doesn't work as well - use medium course grind) in a non-reactive container (mason jar, stainless steal bowl), and add 1 1/2 c of water. Stir so all the coffee gets wet, and leave soaking for ~12 hours. Note that I use a higher concentration then the link suggests.
When the soaking is done, poor through a fine strainer, cheese cloth or coffee filter. I used a strainer on top of a coffee filter sitting in a funnel - the strainer keeps the filter from getting clogged, and the funnel holds a lot of liquid which forces the coffee through the filter more quickly.
Toddy makes a pitcher/filter combo that looks like it will make the process easier, but if you're just making ice cream or iced coffee occasionally, it's probably not worth the 30 bucks.