I managed to get the script to work on my Unibody Macbook Pro by following the author's instructions, and by modifying the script slightly.

I opened the Battery Icon X86.AdiumScripts package, and changed the line:

set «class AusI» of every «class acct» to tifimagedata -- sets the buddy icon

to:

set image of every account to tifimagedata -- sets the buddy icon

Works great!