You can use which ever type of liquor that floats your boat to make jello shots. One factor to keep in mind however is alcohol content. Too much alcohol may result in the jello not being able to set properly.
If you are using the traditional Crown Royal, you'll be fine following my recipe and substituting it for the Irish Whiskey. However, if you are using the newer "Crown Royal Black" (which has a higher alcohol content at 90 proof) you will want to use a tad less alcohol and a bit more water to allow the gelatin shots to gel properly. I hope this was helpful, and if you need further assistance please ask. I'm more than happy to help if I can. Enjoy your jello shots, and feel free to check out my other jello shot recipes through the links below.
Strawberry Daiquiri Jello Shots Recipe
Delicious Jello Shot Recipes With Rum