You first need an external renderer, from Irrlicht or whatever, that is able to render DirectX meshes. Then you use the render material event for calling the external render function with the current entity mesh. This way the external mesh renderer will draw the mesh into A6's back buffer, instead of A6's own mesh renderer. I think it would not make much sense with Irrlicht, which probably renders meshes slower than A6, but it would work.