[web2py] Customizing auth.login form to specify class or id other than default value

[Rohan]

I want to customize auth.login form and create an input field for
username/email like
                  <input title="" type="text"
                    value="username" name="username" id="username"
class="alignright"
                    onfocus="if ( this.value == this.defaultValue )
this.value = '';"
                    onblur="if ( this.value == '' ) this.value =
this.defaultValue" />

using widget customizations {{=form.custom.widget.email}}, I get input
field like

<input class="string" id="auth_user_email" name="email" type="text"
value="">

is there any way to customizing auth.login form to generate the
desired form as specified above?

I tried using {{=logForm.custom.widget.email.attributes["_class"] =
"alignright"}} but got the error.

Any pointers?