You would have to change the values in this *something* (I got no idea how these statements are called ):

VertexShaderConstant[11]={0.0f, 1.0f, 0.0f,0.0f};

Just change the 1st and 2nd value to the desired speed.
You have to experiment a little though. I'd recommend copying the old values to a text file to have a backup, then try out which values work best.
greets