When services use certificates, the certificates and keys can be stored in NSS databases (which may also be used by the services themselves, as well as Identity Management).
Create the NSS databases.
$ certutil -N -d /path/to/database/dir
Request the certificate using
certutil, an NSS tool.
$ certutil -R -s "CN=client1.example.com,O=EXAMPLE.COM" -d /path/to/database/dir -a > example.csr
If the IdM domain is using Certificate System for its CA, only the CN of the subject name is used. With a self-signed CA, the subject must match the configured certificate subject base. The IdM server rejects requests with a subject base that differs from this value.