[eluser]jedd[/eluser]
Hi Tommy and welcome to the CI forums.
Your best bet is to generate your 'view partial' in a common place, rather than in just one of your controllers (and then try to extract it from there each time).
My preference is to [url="http://ellislab.com/codeigniter/user-guide/general/core_classes.html"]extend the core Controller[/url] and put things like your login-form generator into it, load the view partial there too, and then you can access the resultant 'string of HTML' from any of your controllers.
I discuss this approach in some detail [url="http://codeigniter.com/wiki/Header_and_Footer_and_Menu_on_every_page_-_jedd/"]in the wiki[/url], too.