Maybe some of you already got it working, but I was having some trouble with it and now it's working, so I thought I'd post the settings just in case someone is looking for it.

Account title*: iCloud
Name: your name
User name*: your iCloud email address (example@icloud.com or example@mac.com)
Password: your iCloud email password
E-mail address*: your iCloud email address (example@icloud.com or example@mac.com)

Incoming server* (IMAP4): imap.mail.me.com
Secure authentication: Checked
Secure connection: SSL (IMAP4S)
Port: 993

Outgoing server* (SMTP): smtp.mail.me.com
Secure authentication: None
User name*: your iCloud email address (example@icloud.com or example@mac.com)
Password: your iCloud email password
Secure connection: SSL
Port: 587
Use connection-specific SMTP servers: Unchecked