I wouldn't use it alone, but if you must, keep the dose low at about 300mgs/wk and add some test to the combination. I doubt you can avoid gaining weight unless you shed bodyfat and gain muscle mass at the same rate.
Curious, why this particular steroid to use (parabolan/tren) without wanting to gain weight? This certainly is a powerful drug to use alone and also a strong androgen intermediary, but at 100 mg/week, I am not too sure you are going achieve your strength goals and like what you are paying for?