I use a script to just spawn the enemies you want using the spawn command. More than one enemy, then use it several times for each enemy. For instance you could rename the plrinzone script to a new name and add this sort of thing.
-- Player Enters Win Zone
function plrinzone_init(e)
end
function plrinzone_main(e)
if g_Entity[e]['plrinzone']==1 then
PlaySound(e,0)
Destroy(e)
ActivateIfUsed(e)
Spawn(292)
Spawn(77)
end
end
Standard to normal but with the spawn lines added this would spawn the two entites when you enter the zone.
i imagine killing your enemies would be similar just reduce their health instead.
SPECS: Q6600 CPU. Nvidia 660GTX. 8 Gig Memory. Win 7.