finally something about my favorite animal,
fisher are very easy to trap, in my opinion. my favortie set is the famous 5 gallon bucket set with a 220 coniber guarding the entrance. you might want to try and camo the bucket and get it to blend in, but if they're bold enough to come that close to your house maybe not. another idea is a bucket stabilizer, it aids in holding the trap in the proper position, and prevents the bucket from rolling should a coon happen to check it out.
for bait i use a variety of things from deer guts in fall, chicken parts etc. they are a an opportunistic feeder, and it sounds like you don't have a problem getting them to come in, otherwise there is fisher scent on the market you can buy.