Using the ActionView::Helpers::FormTagHelper and ActionView::Helpers::FormOptionsHelper outside of a view

Hi,

I have a utility class (in the lib/media_set/media.rb file in my ruby
application) and in there, I would like to access the
ActionView::Helpers::FormTagHelper.select_tag and
ActionView::Helpers::FormOptionsHelper.options_for_select to create a
select tag. However, in the view files, I can just refer to
select_tag(...) or options_for_select(...) and obviously rails "know"
that these are instance methods on some instance of the FormTagHelp
and FormOptionsHelper classes. I have two questions:

1. how can I use the select_tag and options_for_select methods in my
utility class? Can I use the same instance as would have been used in
the view?
2. how does Rails make accessible or associate select_tag and
options_for_select with an existing instance of these classes in the
view file?

Much appreciated.