Chris Coyier from CSS-Tricks has a nice introductory video on installing and using Compass and Sass on the Mac. http://css-tricks.com/video-screenca...-compass-sass/
Also, if you have problems including some of Sencha's icon set from the pictos folder, you may need to change your config.rb file so it's finding the Sencha framework correctly.
Because of my file structure, I needed to change this...
# Load the sencha-touch framework
load File.join(sass_path, '..', '..', '..', '..', 'resources', 'themes')# Load the sencha-touch framework
load File.join(sass_path, '..', 'themes')