Hmm in main i think you should convert model in hmp format or make new terrain!
And that old sintax works really great too!
function village_func()
{
my.polygon = on;
vec_set (temp, my.pos);
temp.z -= 10000;
trace_mode = ignore_me + ignore_sprites + use_box;
my.z -= trace (my.pos, temp );
}
function sioux_camp()
{
ent_create("tepee_village.mdl",vector(-96,-1164,500),village_func);
}

More easy is give coordinates with vector!
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but how im tried then collision with model is quit unprecise! Possible in some way can do normal collision with models too, but then i need do some experiments!