From what I understand, a Beretta certified gunsmith can make the safety into a decocker only... An interesting side note that I have heard discussed before...
Say you convert your safety into a decocker only, and then you use it in a shooting... Now the other guy's lawyer can try to paint a bad picture of you by saying that you are some kind of gun nut, who modified your gun by removing a safety!!! Does sound crazy, but in today's litigation society, I can see this easily happening... Just a point to ponder...