Jancory,

Try just adding an emit parameter to the original material settings, e.g.

MakeNamedMaterial "ball_1/Preview" "string type" ["glossy"]
"float emit" [50]

"color Kd" [0.576470414797 0.576470414797 0.576470414797]

"color Ks" [0.0250000003725 0.0250000003725 0.0250000003725]

"float uroughness" [0.258086156304]

"float vroughness" [0.258086156304]

Software: OS X 10.8 - Poser Pro 2012 SR2 - Luxrender 1.0RC3 - Pose2Lux
Hardware: iMac - 3.06 GHz Core2Duo - 12 GB RAM - ATI Radeon HD 4670 - 256 MB