If you now want to use Matrix/Riot as your client, you need to accomplish the following additional steps:
- Start Riot and create your account: https://riot.im/app/#/room/#_oftc_#jmc:matrix.org
- Start a chat with @_oftc_NickServ:matrix.org
- In that chat, send register <pwd> <email>
- Validate your Matrix/Riot Nick with OFTC, just like you did your standard OFTC IRC Nick.
- Link your Matrix Nick to your local OFTC Nick created in the first steps by executing the following in the chat with NickServ
link <OFTC nick> <password>
- Log into the JMC channel: https://riot.im/app/#/room/#_oftc_#jmc:matrix.org