I got the Chalice from Belime and hot-footed it over to San Mona where Kingpin lives. I can't get past his bodyguard. How do I get a meeting with Kingpin?

According to this German guide, you have to visit the bar in D5 and Darren will ask you to fight in the ring. After five battles (wins?), Kingpin will ask you to bring him the Chalice. The guide also mentions that this would reduce the loyalty in the whole country.

Once you're up to strength and have some descent weapons, rid San Mona of Kingpin and his men.
Bring the chalice to the Yanni in Chitzena