Utilise triangleSelector!
ITriangleSelector * selector1 = node_ennemi1->getTriangleSelector();
ITriangleSelector * selector2 = node_ennemi2->getTriangleSelector();

IMetaTriangleSelector * MetaSelector;
MetaSelector->addTriangleSelector(selector1);
MetaSelector->addTriangleSelector(selector2);

ISceneNodeAnimator* anim = smgr->createCollisionResponseAnimator(
MetaSelector,
camera,
vector3df(30,50,30),
vector3df(0,-3,0),
vector3df(0,50,0));
selector->drop();

camera->addAnimator(anim);
anim->drop();

Voila!