You can do what you want... only going the other way!
You can import a CS5 Premiere Project (in its entirety
or a selected sequence) into CS6 Ae.
In CS6 Ae:
File>Import>Adobe Premiere Pro Project...
Navigate to your CS5 Premiere project, double-click
and select 'All Sequences', or your preferred sequence.
As Jim points out, Dynamic Linking will only work
between matching versions of Pr and Ae.