Mathieu,
When I wrote "editable by all libraries..", I meant editable-in-the-hard-way (record.abs etc). It would be better than nothing...
I will try to do that next week.
As an initial step, you might consider submitting a patch that adds the hardcoded index and allows librarians to choose which keyword index to use on the OPAC and staff client. This shouldn't be too hard.
I add that as many libraries we are looking forward for SolR, so I won't spend weeks of work for reconfiguring Zebra based search, but even little improvements will be helpful for our users ;-)