Simply raising the object's ambient value doesn't work very well; the object will appear very bright, but only casts light weakly. To get a balance between apparent brightness and light casting, a bit of dirty tricks is needed. For Firefly, using an unseen (not visible in camera) emitter prop works.

In Superfly, no emitter is needed; you can use a LightPath node to increase the object's lightcasting strength. Among the materials in the freebies, there is an MT5 which is not a complete material, but only a cluster of nodes; the idea is that you would add (not replace) that node cluster to your existing material. Zero out the diffuse and specular. Connect your color map into the node cluster, and connect the node cluster's output to the root's ambient socket, with ambient value set to one (or whatever looks good).

I have some lightcasting freebies Some are complete models, some are materials. There also some simple demo props (globes, e.g.) which can be used to kit-bash an existing prop model.

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5