Should I add coffee?

I just brewed this today (Mill Run Stout from Palmer) and was planning on making it a coffee stout for Thanksgiving, but I think it might be a little bitter already and even more bitter possibly with coffee. I plan on trying the cold brewing method to make the coffee. Could I add coffee to the 2ndary without making it too bitter?

Date: 9/20/09
Category: 13 - Stout
Subcategory: B - Sweet Stout
Kettle Volume: 6.96 gal (S.G.: 1.044)
Boil Duration: 1.5 hr
Evaporation: 1.5 gal
Water Volume Added: 0.0 gal
Final Volume: 5.24 gal (S.G.: 1.059)
Efficiency: 83.38%
Attenuation: 75.0%
Evap/Hour: 1.0 gal
Ingredients:
9.43 lb American 2-row
0.52 lb Crystal Malt 60°L
0.52 lb Roast Barley
0.52 lb Barley Flaked
25.51 g Galena (10.1%) - added during boil, boiled 60 min
14.86 g Chinook (11.0%) - added during boil, boiled 30 min
0.0 ea White Labs WLP004 Irish Stout

Recipe
Original Gravity: 1.059
Terminal Gravity: 1.015
Color: 25.03 °SRM
Alcohol: 5.81%

Try adding the coffee a little at a time, let it age for a few days, taste it and add more if you want. Thats how I added my bourbon to my bourbon porter.

When I saw the title, my first thought was a cold extract/brew. I've never tried it personally, but I do trust Randy Mosher!