There are couple or gotchas installing the latest Open Source Flex and AIR SDKs. Here are instructions to get started
Download the AIR and Flex SDKS
Get Flex from : http://opensource.adobe.com/wiki/display/flexsdk/Flex+SDK
Get Air from http://www.adobe.com/products/air/tools/sdk/
I installed them into /usr/local/flex_sdk and /usr/local/air_sdk
Add their bin directories to your path, in .profile or .bash_profile e.g.
export PATH=/usr/local/mysql/bin:$PATH:~/bin:/usr/local/flex_sdk/bin:/usr/local/air_sdk/bin
Make the compliers executable
sudo chmod +x mxmlc
sudo chmod +x amxmlc
It turns out the lastest version of the compiles scripts are dos terminated lines so you need to do
dos2unix mxmlc
dos2unix amxmlc
You can get dos2unix from macports , sudo port install dos2unix
(bug here :http://bugs.adobe.com/jira/browse/SDK-16699)
Next issue is the samples won’t compile, you will get an error “error while loading initial content”.
You need to update the namespace in your AIR project’s AppName-app.xml file to reflect the new AIR version 1.5:
<application xmlns="http://ns.adobe.com/air/application/1.5">
(from http://blog.sunild.com/2008/12/error-while-loading-initial-content.html)