Daemon and client implementations have effectively supported SSL/TLS for many years now. You can't control whether server links are encrypted (that's up to the owners; in a competently run network they will be) but all major networks have one or more encrypted connection ports. 6697 is a typical choice. On mIRC, prefix the port number with a + to use SSL.

Newer protocols are more feature rich and don't have some of the legacy drawbacks of IRC, of course.