> I can't find any information about how to shut down a database to
> single attachment mode via the services api.
> Can anybody show me the way? :-)

You can do it by normal FB API call
isc_attach_database()
look at DPB constants
isc_dpb_shutdown
isc_dpb_shut_single
isc_dpb_shut_force
isc_dpb_shutdown_delay

Ivan
http://www.volny.cz/iprenosil/interbase/