I've only tested with non-monsters entities but try this on that entity
PHP Code:
set_pev(ent, pev_solid, SOLID_BBOX)
set_pev(ent, pev_movetype, MOVETYPE_TOSS)
set_pev(ent, pev_maxspeed, 9999.0)
I don't know if BBOX it's right for that entity.