How to translate user entered content from DB on no pages multi-lingual site??

I’m wondering what I need to do when developing a package in order to enable its use on multi-lingual sites without pages, i.e. where content is taken from a DB and displayed on a single page.

If the site had pages - no problem, pages are added for each language and then translated. But what about a site which displays data from a database on a single page? I can wrap my own defined string variables in t(), I can define DB columns which store a few words and have them translated. But what about rich text? Can this be solved anyhow?