For the location of the prostate gland you can refer to the Benders’ article cited above, which also explains how to reach it. On the web there is a very good page which describes clearly the shape and function of the prostate gland (http://squidgyp.blogspot.com). This allows me to not be too detailed here. The only thing I cannot agree with is the pressure applied by finger on this gland. In my experience, that pressure should start in a very light manner, and become stronger little by little. You can massage it at least as hard as testicles, till it doesn’t ache. The prostate gland is frequently described as a chestnut shaped gland. This is quite true. Perhaps it resembles more the cockhead, the glans penis, with the difference being that the prostate gland is upside down, its tip is below and its lobes start on sides and are above, like in the drawing of a heart. It is in the lobes that the greatest part of the prostate fluids accumulate during the arousal process. So, as Squidgy suggests, we need to rub gently on the sides. It will help to arouse the gland, and you will see evident consequences in your stud's penis also. You can keep up this massage for some minutes, then, going into a deeper massage, also work on the tips of the lobes, on the highest part of prostate gland. If you do it correctly, he will feel the desire to be massaged with more pressure. His prostate needs to be milked. Do it starting from the sides. His penis will probably become more erect, but you don’t touch it. Let him focus his attention on the prostate gland. Its pleasure is sometimes faint, and can be totally wiped out if you do not concentrate on it. After several minutes, his prostate starts to discharge its fluids into the urethra: in a few seconds you can see the first drop appear on the piss slit. When this happens, you can milk the gland more confidently. Milk it, especially on the sides and top, guiding the fluids towards the center of the gland (http://www.youtube.com/watch?v=oJIUvG08WZs).
There is no limit of time for a good prostate milking. It can last ten minutes or one hour, according to the case (age of the bull, his sexual strenght, etc.). It is nevertheless certain that, when a healthy gland is aroused, it can be squeezed for at least five or six full drops of prostate fluid.