how can I post comments under several names?

My blog is about a fictional university. I want to post some discussion topics as if they were thrown open for the university’s faculty to comment on, and then post the comments these fictional faculty would make. The idea is that my real-life commenters could interact with the fictional characters. I want to make this as realistic as possible.

I found out how to create a list of multiple authors using custom fields so my fictional characters can author posts, but I cannot find out how to do the same for comments. I’ve tried creating them as ‘users’, but would prefer a workaround that didn’t require me to log out and in again every time I want a new character to comment.

Probably neither a common nor important problem, but I’d appreciate any advice.