Particles blending / shaders

I'm working on a particle system add-on called ofxParticleDesigner.
It plays particles emitters created with "Particle Designer" from 71squared on Mac OS.

The code and example project (of 0.9) is here
https://github.com/quadbyte/ofxParticleDesigner

The particle system works fine but I'm having a hard time implementing the different blending modes available in the editor.

The good news is there is a working OpenGL ES 2.0 example available from 71squared
https://github.com/71squared/ParticleEmitterDemo-ES2-ARC

It would be great if someone shader savvy could help me port the OpenGL part. It's a matter of initializing a shader properly.

The interesting bits are in
https://github.com/71squared/ParticleEmitterDemo-ES2-ARC/tree/master/ParticleEmitterDemo-ES2-ARC/Particle%20Emitter

Thank you.