For me , in the Flash CS 5.5 and Windows XP, what worked was:
1º: Install the Gaia via Extension Manager.
2º:
Copy the folder:
C:\Documents and Settings\user\Configurações locais\Dados de aplicativos\Adobe\Flash CS5.5\pt_BR\Configuration\GaiaFramework ( pt_BR because i am in Brazil )
to:
C:\Documents and Settings\user\Configurações locais\Dados de aplicativos\Adobe\Flash CS5.5\en_US\Configuration\GaiaFramework
3º: Open Flash CS 5.5 and go to menu: Help > Manage Extensions...
The Extension Manager will open again, but this time the Gaia checkbox will be not checked.
Check it!
One dialog window will open asking to overwrite the present files in en_US folder, click in YES button.
Restart flash and be happy

( Maybe installing direct from flash can solve all the problems, but i did not test... )