Do you already have snow leopard installed and want to upgrade or will you be doing a fresh install of lion 10.7?
I'll be doing a fresh install
Unfortunately there is no fresh install unless you have the correct iBoot disk and a Lion CD. I could not find any Lion support or downloads on the apple website either. Why not just go up to Mountain Lion? In my opinion the easiest install is to go from 10.6.2 to 10.8.2.