IF you are alright with NPCs, disguising as monsters, that can be killed, then this may do it:
(put this inside any working NPC script)
monster "prontera",188,197,"Poring 1",1002,1;
syntax:
monster <"map name">, <x>, <y>, <"display name">, <mob id>, <amount>[, <"event label">];
source: http://rathena.org/wiki/Monster