I know that in premiere CS5.5 is possible by opening the CS6 project file in a txt editor and ajusting a value, i would like to know if there is a similar way for the project files from AE CS6?
No, but you can save AE projects one version back from CS6 to CS5.5.
In After Effects CS6, to save a project that can be opened in After Effects CS5.5, choose File > Save As > Save A Copy As CS5.5.
Details are here:
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