Use the /oper command to attain this.
+i - Designates this client 'invisible'.
+g - "caller id" mode only allow accept clients to message you
+ +G - "soft caller id" mode - same as +g but automatically allows
+ anyone who's in a common channel with you to message you.
+w - Can see oper wallops.
+B - Marks you as a bot in /whois.
+C - Prevents you from receiving CTCPs other than ACTION.