I'm sure there are many more experienced ladies who will know more than me Shylass!! But plenty of lads might flinch or even squeal like girls at the idea of their balls being "milked". Most of them like their crown jewels to handled gently; stroked, caressed, licked and even softly fondled and sucked.
Prostate milking really involves venturing behind the balls to the perineum and stimulating that area around (and in) the man's anus, so is a totally different can of beans. Although with the right lad he might be your slave forever if you manage to pleasure his balls and prostate at the same time! ;)
The best "milking" of my prostate was done by a MD when he was giving me a physical for one of the many jobs I've had. I made a thinly veiled comment, something to the effect, "I wish my wife could do that!" He did not respond favorably, so she never learned the secret. You need to find a friendly proctologist and get him/her to teach you how to do a prostate exam!