openpegasus password file

Is there any way to use an existing password file, like shadow on linux
systems? As cimserver requires all its users to be valid local system
users, it is tricky to permit users to change their passwords...

Generally, why does pegasus require all its users be valid local users?
As we have a quite dynamic set of pegasus users, it's a big effort to
manage this....

Best regards
Anton Hergenröder