Just so you know, that the particle emitter isn’t a fluid simulation. You may get some very simple fluid like effects, such as a fountain, but it will be pretty limited.
I don’t think you can export a particle emitter directly, and I don’t know if Poser can handle metaballs in their raw form. You could use the metaball modeler and create something that can be converted to a vertex modeler, but that’s different than what the particle emitter does. I’ve never heard of anybody trying to “bake” a particle effect to use in another program, so I’m initially thinking it can’t be done.
Is there a reason you can’t make your scene in Carrara and animate it? At the very least, can you render an animation of the emitter under similar lighting conditions and use that to make an animated billboard for use in Poser?