First of all, I don't have the AppGameKit yet (I plan on getting it soon

) so this is going by the documentation only.
However I've been going over the particles commands and I think I see how you could accomplish that.
You could create a particle emitter and set its frequency to some ridiculously high number, 20000 for instance...
Then set the max number of particles for the emitter to 100.
The emitter will create your 100 particles in one frame and then stop creating new particles.
Example:
CreateParticles( ID, x, y )
SetParticlesFrequency( ID, 20000 )
Be sure to limit the max number of particles for that emitter to 100 or you'll have an out of control emitter pumping out 20000 particles per second.
SetParticlesMax( ID, 100 )
And that should do it...