adding html code to category value can it be done?

Hi
I need to ask a naive question. I’m looking to add a category to a custom post but as well as the category, I want to add additional html. I will explain – my site is a sports site and in my ‘Match’ custom post type, I want to add a category of ‘Opposition’ (the team to be played). What I want is that the post then carries an html link for the oppositions website but this code is added to the post – are custom fields the way to achieve this? I’m using the Just Custom Field plug-in but I’m not sure how to add html as a value?

Thanks