Load transfer is completely automatic in ETABS.  Althoug V8 is much better than V7 in doing this, all you have to do is: Define the slab type.  It can be either membrane or shell.  Membrane has the advantage of automatic meshing in V7 but it won't capture any out of plane behavior of the slab.  If you decide to use shells then you will have to manually mesh the slab for the load transfer to occur.  Note that you do no need to define one slab per bay as in previous versions of ETABS.  You can define a single slab for the whole floor and the meshing process will assure proper load transfer to the bearing elements (Beam, walls or columns).

I hope this was useful.

Amadeus