How do I get onmouseenter to trigger even if another collider is blocking th?

Well you could just use layers, and ins$$anonymous$$d of onmouseenter, you use a click and raycast method like this, and just define the layer to ignore in the raycast.

 if ( Input.Get$$anonymous$$ouseButtonDown (0))
 { 
     RaycastHit hit; 
     Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition); 
     if ( Physics.Raycast (ray,out hit,100.0f, layeToIgnore))
     { 
         $$anonymous$$yClickableObject $$anonymous$$CO;
         if ($$anonymous$$CO = hit.transform.GetComponent<$$anonymous$$yClickableObject>())
         {
             $$anonymous$$CO.ClickObject();
         }
     }
 }