I've been using the LaTeX bundle successfully with TextMate. But I have come unstuck when I want to install a new font, for example Garamond. 
From http://www.ctan.org/tex-archive/fonts/mathdesign/ I see I must;

(1) Install a package  called mathdesign
(2) unzip the file mdugm.zip into the root directory of my texmf tree 

My questions to the list are

(1) How do I download and install a package with TextMate / the bundle / using the terminal  ?
(2) where do I find the textmf directory in SnowLeopard ?

Thanks
Lucy .