New slime mob bounce particles

I making a mod that adds ender slimes into the end islands, but i'm confused as to how to fix their particles (and their size but that's a different problem). As of right now, when they jump, the green slime particles play. I want it to play either 1. a custom particle effect (i know slime use slime balls as a particle, and i wish do the same with my ender version of them), or 2. if i can't get a custom particle to work, use a the portal particle effect. How would i go about doing this?