If the EnGarde Installer locates a NIC but fails to initialize the card properly you will be brought to this dialog box below at the start of the networking module.
This will list for you all the cards found in the system that failed to load properly. Since EnGarde requires at least one NIC device be present during install you will have the ability to force an ethernet device to be configured.
To forcefully add the device select the Add button from the dialog box. Upon doing so a new box will be displayed.
This new dialog box will allow you to choose one or more network cards to add to the system. The list-box in this dialog box allows you to select multiple network cards to be added at the once. This interface works identically to the one mentioned earlier in the package selection section.
After selecting your devices hit Add Card(s) and if you added every available card you will be brought to the main network menu.
If you choose to not select all the available cards, you will be returned to the previous menu where you can choose to select the remaining cards or continue on to the network configuration at this point.