"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.
since you have particular, you could use that and a layer emitter.
to use text as a layer emitter, you'll need to pre-comp it (unless that's bee fixed in a later version of particular), so pre comp you text layer and make it 3d.
add a new solid and add particular to it.
in the emitter settings, choose:
emitter type: 'layer'
layer: [your text layer]
velocity random: 0
velocitiy fomr motion: 0
emitter Z size: 0
in the particle settings:
life: 1 (or relatively short)
particle type: 'star'
opacity over life: pick or draw a graphic that fades in and out
set that layer;s blending mode to add and you should get pretty close to what you are looking for.
you could also adjust life random, size random, size over life, maybe even opacity random to see how that effects the overall look.
if you wanted you could looking to making a custom star particle.
another way you can do this is with fractal noise and trapcode starglow. simply duplicate your text layer (no precomping required). add fractal noise and adjust the brightness and contrast to crush the blacks, to leave just smallish specks of white, and animate the evolution setting. then add starglow and set the layer's blending mode to add.
you'll need to tweak the evolutions, brightness contrast and straggled settings to get the sparkles the way you want, but it's a pretty effective method.