To use NetworkManager for your network connections:

1. Disable any previous network scripts in rc.conf (except for loopback)
2. Add networkmanager *after* dbus
3. Create your network configuration files in:
   /etc/NetworkManager/system-connections
   The syntax is described here:
   https://projects.gnome.org/NetworkManager/developers/api/09/ref-settings.html
   and here:
   https://developer.gnome.org/NetworkManager/unstable/ref-settings.html
   The post-install script creates a sample config for each of your interfaces.

Note: To use networkmanager for wifi connections you must compile
      wpa_supplicant with DBUS support.
      At the time of writing, the port in opt doesn't have it.
      See this feature request to find out more:
      http://crux.nu/bugs/index.php?do=details&task_id=957