Bit of a late reply, but...

I have a Trixale whole plate camera with a very simple attachment method for the film holders and screen.
The screen and holders have a lip about 1/8" thick and 1/8" wide down each side. On the camera back there are to screws with large heads on the left and a turnbuckle on the right. The plate holders or screen sit in a slight recess in the camera back to hold them in place and also to provide a light trap. Very simple and it works.

... or have you sorted it out already?