I just use a pattern to turn the first leg, then use it as a pattern for the other four. On a table they only need to be close as they are not next to each other. You can also make a template out of thin wood to the reverse profile of the work, then as you turn your work you check periodically to make sure the profiles match. The template works well when you are starting out at turning but you will find that they take more time than they are worth and you will eventually turn them by eye. Good Luck
most likly the quikest way will be turn them by eye.there's several different template/jigs you could use, but like everyone said they are so far apart the human eye wont notice.as long as you don't get in a hurry you'll do fine.
Just yesterday, we used clamps after glue simply to take the bow out of the wood we were using, and it straightened everything out for us. Usually though, any time you lay up a project the clamps are...