I think you can use the Milkshape modeler to convert from some of the game formats - whether it works the other way I don't know. You may have problems with the sizes though - most of the Poser figures AFAIK have way more polygone than most game figures. Geralday has some low-poly figures that might be more appropriate.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken