Using Depth of Field with 'Poster' Render?

I found VIoxitar’s little tutorial about using soft lamps recently and thus learned about the Poster command. I’ve experimented with it a bit to use it to make better pictures, but was wanting to incorporate Gmod’s in-game Super Depth of Field post processing effect into these sorts of pictures. So far the only workaround I’ve figured is to take a regular screenshot with the SDOF and then layer it over the poster render, but that dosen’t really look as good. VIoxitar mentioned that the regular poster command could potentially be made to work with SDOF, but I haven’t been able to find a way to make it work yet. Anybody know how to do this?