Check out Marcello’s great AU class from last year. http://au.autodesk.com/au-online/classes-on-demand/class-catalog/2015/revit-for-construction/cs10612#chapter=0
joining the dots between posts:
I watched the lecture that you provided the link and i downloaded the package (break slab by model line) but it is working only on default revit files on Level 1 but from the moment i change the level it doesn’t work anymore.
It looks like the package Break.Slabs.at.Modellines was written with the level hardcoded as level 1, and possibly it only works in the XY plane (Z=0)
Assuming you need to do this for 4D using Navisworks
If your construction (slab) joints are consistent vertically- I would recommend splitting the model by exporting section box views to NWC files.
for example, you might have a separate structure south and structure north models.
You can then sequence them separately.
This also has the benefit of splitting other elements such as beams or shear walls.
The other answer is to use a better 4D tool (such as Synchro) which will allow model elements to be split across tasks