If you dont want randomization, the simplest (and probably not what you need) is to make use of the Time node and Sin node within the material to drive the emissive channel. But this will only give you a very basic periodic pulsating effect.
But if you are ready to play with material params, then you can use the ParticleColor, ParticleAlpha etc node within Material editor and use it to drive your emissive and diffuse channels. The actual values for these two are then controlleld from corresponding modules in cascade, where you can achieve the necessary randomization and other stuff.
yet another solution is to make use of a mask texture. Use texture that looks like a cloud or something like that. Then connect a panner to it. Multiply its output with the calculated emissive and plug it in emissive channel. By changing the texture, you can have different types of sparkle. Randomness can be achieved by manipulating the panner speeds using an exposed material param that can be controlled from cascade (ParticleColor or ParticleAlpha cane be used as well).
I would suggest you to go through this simple tutorial: