How can i mirror a particular branch in one Subversion repo to a particular branch in another repo?

EDIT:

Actually, after playing with Timeline some more this is going to be a non issue. The UI is confusing because its not necessarily meant to work with multiple repos, but it does work since each project relies on the normal svn metadata for the reop URL (DUH). I dont know why i was thinking i needed to go to extremes. Ill leave the question open for a bit to ssee if this is even do able, for general reference.

I'm trying to figure out a way to integrate PxelNovel Timeline into my existing workflow because an agency ill be working with will be using it.

The problem is Timeline is based on the idea that there is a single repository which contains multiple projects, so it doesnt support multiple repositories. So what i would like to do is something like this:

Repository A (Timeline):

design-projects/
  project1/
  project2/ 
  ...

Repository B (Project 1):

project1/
  trunk/
  tags/
  branches/
  design/

So what id like to do is set up some kind of post commit hook, or a cron job that copies mirrors design-projects/project1 to project1/design with all the history and what not. Normally something like this would be cause for an svn:external, but i want all the commit info from the Timeline repo to show up in Redmine which an external will not provide.