Steam

Hello, I have a mca from late 2010 that I use for some games on steam. Because of the fact I have a 60gig ssd I want to install the games on a external hard drive. I have followed the macrumors tutorial with Source Finagler. But when I boot up steam after i followed the exact instructions, I get a error that Steam requires the steamapps folder to be on a case insensitive system. Any help?

EDIT: I am using Mac OSX 10.8.3