From my experience catching swarms:
1) If they are clustered, you can go ahead and get your sugar water spray bottle ready and put the box near the tree
2) Spray them and knock them into the hive. Then sit back and wait as the rest work their way in, then close it up and move it to where you want it.
3) Keep it sealed over night and feed. Once they fill out the comb you've given them add another super and feed until its drawn.
That's what I would do
1) If they are clustered, you can go ahead and get your sugar water spray bottle ready and put the box near the tree
2) Spray them and knock them into the hive. Then sit back and wait as the rest work their way in, then close it up and move it to where you want it.
3) Keep it sealed over night and feed. Once they fill out the comb you've given them add another super and feed until its drawn.
That's what I would do