OK looking at the code to CSNadeDrops (
http://forums.alliedmods.net/showthread.php?p=70493), I think there's some stuff in there to help. This appears to create an entity (a hegrenade in this example):
Code:
new grenade = create_entity("info_target"); // create grenade entity
entity_set_string(grenade,EV_SZ_classname,"fake_hegrenade"); // change name
entity_set_int(grenade,EV_ENT_owner,id); // set owner
entity_set_int(grenade,EV_INT_iuser1,0); // hasn't bounced yet
// set grenade entity's size
new Float:minbox[3] = { -2.5, -2.5, -2.5 }
new Float:maxbox[3] = { 2.5, 2.5, 2.5 };
entity_set_vector(grenade,EV_VEC_mins,minbox);
entity_set_vector(grenade,EV_VEC_maxs,maxbox);
// set grenade's overall being of a whole
entity_set_int(grenade,EV_INT_solid,SOLID_TRIGGER);
entity_set_int(grenade,EV_INT_movetype,MOVETYPE_TOSS);
// set a random angle
new Float:angles[3] = { 0.0, 0.0, 0.0 };
angles[1] = float(random_num(0,180));
entity_set_vector(grenade,EV_VEC_angles,angles);
// get player's origin
new Float:origin[3];
entity_get_vector(id,EV_VEC_origin,origin);
origin[0] += NADE_OFFSET; // offset
// set model and origin
entity_set_model(grenade,"models/w_hegrenade.mdl");
entity_set_vector(grenade,EV_VEC_origin,origin);
There appears to be more code regarding if another player picks it up in that link.