Can you just get a job at a music store and learn from one of the techs there or do you have to take some classes (provided by said store) for it? Or does it really depend from store to store? I'm thinking of getting a job at a music shop, so was wondering.
From what I believe, to have a good chance of getting the job you'll need to be a certified technician through some school. That and alot of experience with guitars. You're gonna have to walk in there with a resume that says you know how to fix guitars, in other words.

If you are just starting off fresh and you want to pursue this career, just try to get a job as a service clerk at a guitar shop. Take some classes at a technical school while working there and try to move up in the guitar shop you will be working at. I'm sure if you hold the service clerk job for a while, prove you're a good worker, and get one the managements good side, they will move you up once you become certified. This will get you some experience in that field for you to move on. Once you are certifed, and have some experience, you can move on to bigger and better things, like working as a tech for a big company or even starting your own business.
Read the guides (there are many online), practise on your guitar and your friends. Then get chummy with the techs at your local shop and offer to help out, unpaid work often turns into paid work when an opening turns up.

Learn to set up a guitar properly, how to plug a hole for when you replace the strap button, how to adjust a trem and how to shield the electronics. Once you have those then go and get chatty.

They should be able to teach you refretting, scaloping, refinishing (they might not do refinishes though) and rewiring. Then again all this information is available on the net so you only need a job if you either want to get paid for it or if you want lots of practise.
The shop I plan to get a job at, I've been going to for years. I'm friends with the main tech guy and know most the staff pretty well. I'm just not sure how the whole "working on guitars in the store" thing works and its hierarchy. Thanks for the advice.
In that case, just ask to help out next time they do something - even a basic setup. If you want to tech roadie style you'll need to either get in with the bands (unlikely) or get some experiance on your CV and join a backline company - the ability to lift amps is good if you join a backline company (also the health and safety training for lifting heavy objects).
No, I mainly just want to do it for my own personal use. Working there would just be for discounts and extra cash.