I've done 2 installs outside on the driveway and 2 in a garage.
Either way give yourself about a good 6-8 hours if you've never done anything like this before. If you follow the directions to a T, you should be fine.
Good set of tools (power) and you're all set. Make sure you also have an extra set of hands for the moral support too.
I know Bulldog-yota has a great write up of the installation so PM him for more details. You might also want to find some local members that might be able to give you a hand.
Good luck!