Irssi

First, add the Xinutec network to your configuration with the following command: 

/network add xinutec

If you want to just connect to the network, enter the following command: 

/server add -ssl_verify -auto -network xinutec irc.xinutec.net 6697

This will add the server and connect to it automatically whenever irssi is started (because of -auto). In order to add the changes to your config file, you need to use 

/save

As the last step, you probably want to connect to the network: 

/connect xinutec

All done!

Here's an example of what the default configuration of irssi looks like:

Using a client certificate

This is only required if you want to register your channels because you're a channel operator.

SSL client certificates are our official way of registering channels and handling channel access control. Please read this article along with the article on channel modes before continuing with the irssi specific instructions below.

Assuming you followed the instructions linked above, you now have a client certificate with associated private key, so save them both in ~/.irssi/client.pem by concatenating them with the following shell-command: 

cat key.pem cert.pem > ~/.irssi/client.pem

and use the following irssi command, all on one line: 

/server add -ssl_cert ~/.irssi/client.pem -ssl_verify
            -auto -network xinutec irc.xinutec.net 6697

If you aren't sure what these flags do, take a look at /help server

In case you already registered the network and server in your client, you can either remove the server with /server remove irc.xinutec.net and re-add it as above, or manually edit the configuration file ~/.irssi/config using your favourite text editor, so that it contains a section like this in the servers list: 

{
  address = "irc.xinutec.net";
  chatnet = "xinutec";
  port = "6697";
  ssl_cert = "~/.irssi/client.pem";
  autoconnect = "yes";
},

If you later decide that you don't want to use a client certificate, simply remove the line that starts with ssl_cert.