The borrower imports script driving the staff client import tool has a large number of bugs attached to it to add features. I propose a refactor to aid in this work. I have been working on a brach to factor out the import code into a module, and add a new command line script under misc to enable regular background user imports. The git branch is available here: https://github.com/mrenvoize/Koha/tree/borrowerImports It is very much a work in progress, though allot of the base code is written.
I abandoned this refactor a long time ago now.