You can use all kinds of simple connectors. Like, a couple of stainless spoons. Any metal object. You can also use a pair of T.E.N.S. pads (http://www.vitalityweb.com/backstore/electrodes.htm). If your Zapper happens to have an alligator clip on the two output wires, you just clip to ... whatever taps your drum.
No matter what you use for a Zapper (ranges from a $10 Zapper to an F-Scan 2), you want to wash your hands before a session, drink 4-8 oz
of water or, better yet, GatorAid (an electrolyte). Some folks wrap a moist "pad" of some kind (gauze, cotton cloth, etc.) around the interface (not with pads - not needed) to improve connection.
One last thing - how do you know ANY Zapper is working? The only way that I know is to have some electronics technician attach it to an oscilliscope. All TV repair and some appliance-repair shops have them and to test a Zapper only takes a few seconds. Now all you have to do is convince them to do it!