# rhnreg_ks --serverUrl=https://YourSpacewalk.example.org/XMLRPC --sslCACert=/usr/share/rhn/RHN-ORG-TRUSTED-SSL-CERT --activationkey=<key-with-rhel-custom-channel>

File "/usr/lib/python2.6/site-packages/rhn/SSL.py", line 230, in write sent =self._connection.send(data)
<class 'up2date_client.up2dateErrors.SSLCertificateVerifyFailedError'>