It shouldn't be a big deal to do, BUT you need to be kind of careful. As already stated automotive lighting uses fairly high amperage, and the switches in your car are only rated to a certain amount, overloading will cause smoke loss, and that is a bad thing.

Before you begin you need to take a close look at a wiring diagram of your vehicle. Ideally you will want to change the wiring to a relay, making sure that the relay doesn't share switched feed with another high draw circuit. Like any electrical (these systems are not electronic) issue in a car, you should be fairly sure of where you need to put your test light and which wires will be getting moved before you take out the first tool, otherwise you are likely to end up sending your car to a shop on a hook, and paying a lot of money to fix mistakes.

I am not trying to be condescending, but I have seen it many times. Vehicle wiring is simple stuff, but if you get teh slightest bit confused you can cut a wire, blow a fuse, fry a relay, or disturb a ground, any of which can make your car inoperable, and can be difficult to troubleshoot to an automotive novice. If you wonder why I pointed out that vehicle lighting circuits are electrical not electronic, or don't know the difference, you are likely not qualified to start modifying crucial systems in your car.