How change username by email field in order to login on front-end???

Hi I'm using package Login 1.8.1.

http://rtfm.modx.com/extras/revo/login/login.tutorials/login.basic-setup#Login.BasicSetup-LoginPage%281%29

In the Login Tutorial , use default fields on lgnLoginTpl Chunk: username and email.

<label class="loginUsernameLabel">[[%login.username]]
<input class="loginUsername" type="text" name="username" />
</label>

<label class="loginPasswordLabel">[[%login.password]]
<input class="loginPassword" type="password" name="password" />
</label>

What can I do if I want to use email and not username field to login?
Any idea?

You can use the email address as the username in the first place.