This is the “true” Eden way of adding emitters, via an entity's attributes.
Not all entity types are supported (those on which it would not make sense to have these attributes).
Map objects are also not supported. It is not possible to edit the parameters of these emitters from within the attributes, but it is possible to edit them via the Emitter 3Ditor after setting them up.

So, let’s pick for example the BMP2 Wreck (Props → Wrecks → APC) and open it’s attributes.
Expand the section Emitter 3Ditor, tick the Use object as emitter box and the following should activate: