aptanascss

That's my personal best way to manage the sass/scss compilation within Appcelerator Studio.
It should work in every IDE derived from Eclipse (like Titanium/Appcelerator Studio).
The only prerequisite:

$ sudo gem install sass

Many tutorials/how-to that I've read are using compass or ant to achieve one simple task: to compile automatically a sass/scss file every time I save it.
Fortunately this can be done using the "external builder" feature inside Eclipse.

How to do it the easy way:

1. Clone the repository

   $ git clone https://github.com/frazei/aptanascss.git
   

2. Link the binary to your path

   $ ln -s ~/Documents/GitHub/aptanascss/aptanascss /usr/local/bin
   $ chmod +x /usr/local/bin/aptanascss
   

3. Go to the root of the project and then..

   $ mkdir .externalToolBuilders
   $ ln -s ~/Documents/GitHub/aptanascss/Aptana\ Scss.launch .externalToolBuilders
   

4. Enable the external builder: select the project > Properties (⌘ + i) > Builders > Check "Aptana Scss" > Click "Apply and Close"

Repeat step 3 and 4 for every project.