I've heard Bounce Dryer Sheets work. I guess zip tie 'em under the hood somewhere. That Critter Ritter certainly sounds like it's worth a try.
It may be more humane to go ahead and shoot squirrels. A little egg, some pepper, flower and fried, they're pretty tasty. Squirrels are territorial. Moving them to another's territory only causes problems elsewhere, too. Fights and lack of food to sustain both the new and existing population is a sad way to go. Ask your local County Animal Shelter about euthanasia if you gotta trap one. Sometimes, they'll loan you a trap, you bring it back with a critter and it's done, so to speak.
Do what you gotta do. I kinda feel like trying to erradicate squirrels is spittin' in the wind. Localized deterrent treatment seems more reasonable. However, there are the occasional home invaders that may require "re-assignment".