I currently have an imperial stout almost read for bottling, and was planning on using Kahlua as my priming agent instead of corn sugar. I had seen an post on some forum or web site where someone had done that and I thought that it sounded like a great idea. I vaguely remember finding a web page that listed all sorts of priming agents but I can't seem to find that page anywhere.
The only "calculation" that I did find was someone who suggested that what you could do is figure out how much sugar is in Kahlua per fluid oz, and then figure out how much sugar you'd normally add using any one of a number of online calculators, and add that much to the beer. With 2.1 CO2 volume, and 5 gals it works out to be about 3+ oz of sugar, and 11.2 grams of sugar/oz works out to be about 8-9 oz of Kahlua.
I realize that this is assuming that the only fermentable sugars in the Kahlua were those listed on the site that I found, but it's probably close.
Does this seem like it would work?