I did it few years ago, and as I remember I did the following
1) created my own template in forlder
src/template/_theme_/_template_.ftl
theme - it is name of theme used in struts tag definition (see below). E.g. ajax (already defined and existed in Struts2 theme)
template - name of your template. E.g. inline-submit:
src/template/ajax/inline-submit.ftl
2) now in jsp, when I want to show that some tag should use that template, I wrote the following:
<s:submit theme="ajax" template="submit-inline" ... />
that's all.
In your case you need to write something like that:
<@s.textfield label="E-mail" name="email" theme="_DEFINE_WHERE_TEMPLATE_IS_LOCATED" template="text_login"/>