Comic Life not only allows you place the tail's end point where you want, it also allows you to bend the tail's shape to a different shape in order to fit your layout better.
To position the tail's end point:
To bend the tail:
In the example above you'll notice that a red circular handle appeared once you clicked on the tail—this is the reshaping handle. It allows you to bend the tail in a variety of ways to suit your needs:Tip: Try to keep the tail away from the speaker's face so that the tail is pointing to the source of the words, rather than touching it:
Tip: See the Form Inspector for more tail related options.