first of all, learn power chords, and pentatonic scales,
then you need to practice your rhythm skills, untill your fingers will bleed
than learn some double stops (which are playing 2 strings together while soloing, like in johny b.goode), and listen to lots of their music...
i think the coolest thing about ac/dc is their riffs, which are easy to play, but yet they have their magic, so in the minute you can play malcolm's parts you will be able to play angus' solos