[support] Allowing users to create content that is always tagged with a taxonomy term based on the user.

Hi, I am trying to create a product/ad website where the actual manufacturers add their own content. I want to give these manufacturers a login and the content they create be tagged with (uneditable) their manufacturer tag. I thought I'd ask in the support forum first in case there is a feature I've missed, but I'm suspecting I'm going to need to write at least a little bit of code. My first step would be to use content profile I guess to link taxonomy terms to users and then for my node use hook_nodeapi() to alter it based on that (maybe also hiding the actual taxonomy field for that user). Does that make sense or does anyone know a better way to do it? Thanks, Anthony.