Hello, please help me.

i want to install some footwell LED's and i want to connect them through my dome light fuse. i want the cool dimming affect when you lights go on and off. I have just recently purchased my Aveo5 and i have no idea about how to about tapping into the wires. if i use a wire tap will i get the same affect as if i physically tapped into the wire. Where are the positive and negative wires for the dome light? i really don't want to have to run a cable through my vehicle all the way to the light. help would be greatly appreciated