[header] How to dual boot mac os x lion [title] Download mac os x lion from the mac app store. [title] Navigate to applications] utilities] and double-click disk utility. [title] Select your hard drive in the left pane of disk utility followed by the " partition " tab from the right pane. 
[title] Click the " + " button to create a new partition and give it a name format and size. [step] Note: your format should be mac os extended (journaled).