Catching a swarm of honeybees may seem intimidating at first, but this is the time in their lifecycle that the bees are at their most amenable to handling. Their priority mission at this time is to find somewhere to live, so if you provide them with a suitable container, they are more than happy to move in and set up home.
This video shows a way to catch and house a swarm using a straw basket with top bars, which can later be lifted straight into a top bar hive with little disturbance to the bees.