Actually no the case will have 4 holes punched but there will be a plate that you can mount to cover the 2 holes not being used.
The 4 pin connector that you are seeing is supposed to be for power and I just installed it in there to see if it fitted properly. There will be another plate provided to adapt the IEC hole to a 4 pin connector.
So essentially you will use the first 2 XLR holes to mount the Line in and Line out, cover the next 2 with a plate and cover the IEC hole with a plate that will allow mounting the 4 pin connector.
This is not a "custom" case but it will be a custom front panel. After I provide Dan with the latest front panel design I'll ask him to post an image for all to see.
If anyone wants to make their own front panel I could provide an Illustrator or PDF file.
Jim