I'm not sure exactly what effect you're going for, but I think you want to use the "Area Emitter Masks" feature in particleIllusion 3. You may also need to use a couple of different emitters: one for the "sparkles" that form the text, and one (or more) for the initial explosion.
The explosion emitter(s) are simple -- no "masking" required.
To make the text sparkles, you'll need an image file of the text with an alpha channel. Then create an area emitter, open the emitter properties dialog for the stage emitter and check the "mask emitter with images" option, then click the "options" button and select the image to use as a mask.
You may need to increase the "number" property after masking the emitter.