knowing the scales positions will show you where to find those nice little notes that will make your dull C major turn into a beautiful C add 9 or sus 4...
You can find basic scale fingerings in the trick section of this site.
As to practice scales, you have to have a strong will, or a friend or teacher that will make you do it... Buy a metronome, and experiment too...
By the way, some players think that chords are just scales played with several notes on top of each other (allan holdsworth is one of them)... So knowing the scales make you play better chords...