Brent,
Try the PETA approach. I did a quick internet search and guess what I found. www.critter-repellent.com , LOL, who knew. Anyways it looks like they have a predator piss repellent that might be your easiest fix, don’t kill em, just make em relocate. You are going to open the dreadful scuttle/hatch/etc. to place the powder in the attic. I wouldn’t shake it all over as much as put a layer in the bottom of several butter bowls for easy clean up. When they vacate the premises repair the hole. The shake predator piss repellent can is $ 15.95. Well worth the investment.
Good luck and happy hunting!
Peace,
Dave
