Easiest way to trap beaver is with castor mound sets, I think. Beavers mark their territory with scent from glands around the anus called castor glands. If alien scent appears in their territory it riles them up. Beavers make mounds around a pond that are from 2-3" to 6-8" high and deposit castor scent on them by way of staking claim.
You can buy castor scent commercially at trapping supply sites on the internet. You just make a mound in a convenient place and smear a little scent on it. Place the coniber 330 at the water's edge in front of the mound which itself would be a foot or two back. Make the mound by raking some pond muck and sticks to add to some dirt. You can take a shovel and dig a shallow trough in the pond bottom that leads from the water up to the mound.You can use that dirt to make the mound. The trough will be like a beaver channel and will lead the beaver right into the coniber. You can also stack some brush to each side of the trap so it is inconvenient for the beaver to go around the trap. If you go to Sullivan's trapping supples website or the Trapperman forums they show pictures of these sets and lots of info.
I have regular beaver invasions here in central Oklahoma and have to fend them off from time to time. Sometimes you can't find traveled beaver paths or channels to put traps in, especially when beavers just show up. By the time they create clear cut paths they may have destroyed a lot of trees. Using castor sets you don't have to wait for them to leave sign.

Layton Runkle