Different path to public document root in Development mode

I know how to do this for actual deployment, but is there a way to
change the Rails "document root" used from its default of RAILS_ROOT/
public *in development mode*?

I want to do something like this:

  config.document_root = "/shared/global/images"

Since I have several different applications using the same image sets.

We can't use svn:externals or other tricks due to some complexities
I've omitted, so I'm hoping there's a way to configure this in
environment.rb

Thanks,
Nate

Is it enough to change the asset host (for serving stylesheets, javascripts etc)?

Copy the line:
config.action_controller.asset_host = ‘http://whatever/
from production.rb to development.rb

Hope this helps.
Phil