Login on Connect
Here's a quick and fast question answer section about what Login On Connect is...

• Login on connect is a little feature on our IRC servers that allows you to login without having to use /ns auth, /auth, /msg nickserv@services.replayirc.com auth and so on.
• Login on Connect is commonly referred to as LoC.
• LoC allows you to login via a /user/pass in the server password field.

How do I use LoC?

• First, you need to have an account filed with NickServ. If you don't have one already, create one on irc by typing /ns reg user pass your@email.
• Next, once you have your user pass combo (and authed)... make sure /ns addmask *@* is added into your NickServ allowable auth host masks.
• After that this is where the fun starts! If you don't use mIRC, just be sure that /yourUserName/YourPassword is set as your server password field. Otherwise, if you use mIRC see the following image below.
• Simply fill out as you would see above under the mIRC options: Category, Servers --> Add. Description: Random ReplayIRC Server. IRC Server: irc.replayirc.com. Ports: 6667. Leave Group Blank unless you want to make it a group and add in additional servers later on, setting it as a category. Password: /username/password. The Password section is where you put your user login on connect information.
  

General Notes
How do I know if LoC logged me in and worked as said? See the following image.
You'll see the server send you a notice stating this:

   

If typed correctly, you'll see the server send you the notice: Attempting service login to NickServ. If you don't see that after the Ident / Host check, then you much likely typed something wrong! If you are typing it manually not via any server password field, use /server irc.replayirc.com:6667 /user/pass.

This is what the screen will look like if the login on connect fails: