You can also do this to create a temp emitter and modify it in real time until it looks good (mission editor addon required):
1. Start a singleplayer game
2. ParticleEditor.initEditor();toggleParticleEditor(1);
3. Close the window
4. Move back until you see a random emitter in mid air
5. toggleParticleEditor(1);
6. Mess with the variables on the gui until your emitter looks good :D
7. Save the emitter
Alternatively you can directly write the emitter datablock which is annoying as hell because you then have no idea how it's going to look and are testing your thing a long time.