Step one: Fall deeply in love. (Deeply in lust will do at a pinch, but deeply in love is better). This can be with your cat, or a landscape, or your five year old daughter, or a man. It is most effective if it is with a man. Nothing will twist in your heart and betray you like your love for a man. Except a cat, that is.
Step two: Have good times.
Step three: Have bad times.
Step four: Brood. Have sleepless nights. (Like this one). Drink; (absinthe makes the heart grow fonder). Lie awake looking at the different colours of grey the world takes on at 3.00 in the morning.
Step five: Stop brooding. Try to define exactly what it is you are feeling instead. This is where the catharsis starts, because you stop feeling, and start thinking about feelings, which is subtly different. Play with words and sentances in your mind when you are walking. Wander distractedly round supermarkets like the daft-biddy who lives down the street. Be unable to settle to anything. The effect you are aiming for is a sort of mental indigestion; you can concentrate on nothing but the rumbles in the back of your mind, but they are in the back of your mind, and you cannot actually get at them. The more this becomes a physical sensation, the better the poem will be.
Step six: Wake up, completely distracted one morning, with the compulsion to splatter the contents of your mind onto paper. It helps if you are crying while you do this. You can do it sitting in a car outside the house you shared with your ex, for added piquancy. If you really want to f**k with a man's brains, get up all distracted one morning, refuse to talk to the man whose bed you are getting out of, (this is simplest if he is too sleepy to handle the situation) and then sit down in the kitchen and write a poem about someone else. This only works if the poem that you write is really good.
Step seven: Read the thing out loud at every available opportunity, both to yourself and to other people. This is when you discover that not only was it mental effluence, it is literary effluence too. But at least you learn which words and lines are redundant, and where the rhythm falters and flags.
Some examples of poetry written this way.
Step eight: (Only do this if you are prepared for the consequences; though the sense of power may make it well worthwhile). Show it to the bastard who inspired it, and watch him edge away in nervous fear.