Top each fillet with a small pat of butter (I use about 1/2 Tablespoon per piece of salmon) and 1 teaspoon of dried dill weed. Add a dash of salt.
Place the packets into the slow cooker (it's fine to stack them) and cook for desired time. Like I mentioned above, I cook frozen 6 ounce fillets for about 3 1/2 hours, frozen 4 ounce fillets about 2 1/2 hours. Don't be afraid to remove one packet and check it if you're getting worried about it being overdone, you can always wrap it up and put it back to finish cooking, or change the setting to low if it's almost finished!
If you don't love the smell of salmon cooking (or are pregnant :) I recommend putting the slow cooker in the garage or back porch. I've been able to eat many a dinner that I wouldn't have otherwise if I'd been smelling it all day by simply letting the food cook where I can't smell it.
I hope you'll try this recipe, it's a unique cooking method that I think you'll love having in your repertoire of dinner recipes!