In order to support the new Omniture workflows, we had to use some new CSXS features and Flash Pro features that were implemented in CS5 only for these extensions to work. Specifically, in Flash Pro, to enable new communication workflows between the design view and CSXS panels, we've introduced several new events that are triggered from design view to update the panels.
We cannot backport these events to CS4, as this would be a very costly endeavor with limited applicability. In order to use the extensions, we recommend you moving to CS5. Aside from the extensions, you'll get also more than 250 great features, more speed, etc.
Regarding the AS2 or AS3 support - we have both for the Flash Pro Test&Target extension, and we only support AS3 for the SiteCatalyst extension.
I hope this helps,