Another way you can try is something like this.

Depending on the version of poser you are using. But with firefly go to render settings. Choose manual settings. Here you turn off cast shadows, Subsurface. and to the right there is a check mark where you can turn on "Toon outline" choose the desired pen width.

For the objects you are rendering make them all white in the diffuse and give them a white ambient color with a setting of 1. Make the ground plane invisible and then render and you get a pretty decent result i think.