I too would appreciate a few pointer in this area having experimented with this in the past. However I have noted from previous non-responses to questions that this forum is a bit of a black hole. We could use a moderator who really knows his stuff. Anyway, a few pointers in the right direction which may help you out.
There is a tutorial here which shows a working example of a scene built up in this way and how to combine the layers.
http://evermotion.org/?unfold_exclus...fold=exclusive
Autodesk also has some short videos on bringing render elements from 3ds max into combustion as well as an intro to RPF files here. They are quite small on screen, but if you've got the Combustion Unplugged bonus DVD you can find them on there too.
http://usa.autodesk.com/adsk/servlet...112&id=5574967
If you want to use 3d post effects such as fog or dof etc. the Combustion help files tell you which g-buffer elements you require for each effect. Then either save everything to jpeg sequences (or targa if you need alphas) and combine using g-buffer builder, or write to RPF file sequence (these can become very large though). Finally layer up your additional passes and set your layer modes accordingly (multiply for ao passes, add/screen for others) and adjust the layers opacity to suit.
To those more experienced please feel free to add to this or contradict me, I don't mind!
