You could start by seeing that jealous can often come from fear: fear of losing your partner, fear of losing control, etc. In a relationship that is built on love and trust, these fears can be stopped. It's not always easy, but it can be done.
And make sure there is a HUGE amount of openness and communication with polyamory, because this is what helps to keep those fears away. Fears tend to come from the unknown, and by keeping the lines of communication wide open, the unknowns are pushed away.
I'm an expert at sexual innuendo. I could keep it up all night.