even though that CityEngine does not have a proper solution for converting 'networks' ( attributed 3d lines ) into nice geometry ( though that's planned ), many of these things can be done in CityEngine.
Then I'd recommend to create the buildings based on CGA code directly within ArcScene ( 10.2 ) with the new GP Tool for this. CityEngine 2013 was just released, so you can use that one to create the 'Rule Packages' that are needed to run the GP tool.
There's also a second GP tool that directly creates a WebScene based on the ArcGIS scene. So basically, CityEngine is only needed to author the rules and create the RPK.
As long as the resulting pipelines are MultiPatches, you can also export them ( together with the buildings ) in a WebScene.