Hi, at the moment there's no shader management at all in SPARK. You can bind a pixel shader while rendering particles to perform special effect if you want (+ binding the normal map).
However for normal mapping, you ll need a normal for the billboard to transform the normal map in the world and as billboards in SPARK are oriented on CPU and the normal is not transfered (for bus transfer saving as lighting is not handled). But as the normal is already calculated (it is the look of the billboard transform), all you have to do is modified a bit the renderer to transfer the normal.
One thing on my TODO list for SPARK 2 is shader management to put some computation on GPU (like billboard orientation or even primitive construction via geometry shaders) and to perform build in effects (reflexion, soft particles, normal mapping, heat effect...). The thing is I m working on the lib in my spare time for free, so I cant tell you when this will be implemented.