Peter, with the right crowd this could be rousing and fun! There's been some discussion about the correct words, etc., on the thread highlighted at the top of the page, "Lyr Req: lion sleeps tonight". As for how to get them singing, the trick is to spend enough time with each part until the group is singing confidently and independantly.
*Rehearse one part, such as the men, then rehearse each next part separately before adding it to the previous parts.
*Wave your arms up and down firmly to maintain the beat, and don't hesitate to slice them apart horizontally to stop the action if they drift from it!
Most folks have heard this song plenty of times, so each part will at least sound familiar to them. If you exude knowledge of the song and confidence in their ability to sing it, they will believe in you and in themselves and have a wonderful time! Don't try to be like Pete S- just be Peter T and you'll be fine!