Right, but jPCT doesn't use the rotation pivot for the billboard effect. Instead, it uses the object's center-of-mass, which is apparently calculated when the object is built. This can be changed either by making the object have more volume by adding polys or by translating the mesh after building.
For the color settings, you would need to somehow specify negative values for the additive transparency mode - you want to add some green after subtracting a bit of red and blue, so the resulting effect is brighter than the initial colors, but not in a way that makes it look white. I'm not sure if there is a one-step way to do that.