Is there a way to merge separate Subversion repositories into a new repository with a different structure while maintaining version history?

We’ve got some projects that are contained in their own repositories but we want to move related ones into a single repository and keep the version history.

The trick is that we need to put each project into the new repository as a directory with its own working structure (branches, tags, trunk). Unfortunately, using svnadmin load/dump doesn’t allow for changing the path of what you’re loading back in.

I’d like to see if it can be done completely with Subversion for the time being but I realise that this would be well suited to something like Bazaar which I am open to suggestions for.