Best way to get just a tiny bit of data from another database

[eluser]Bramme[/eluser]
Hey all,

I'm working on a new website (my second in CI ^^), but I've stumbled upon a problem:

The site has a phpbb3 forum and people who comment on the site announcements or blog entries can enter their forums password, that way their avatar gets shown etc.

This is the only time I need to connect to another database. What would be a good coding approach to this?

Thanks for your thoughts and time!