First I trimmed the doors to fit in the case using spacers.

The hinges were used as spacers along with anything else I could find of the same width.

Chamfering the edges on the fit is complete.

I made a spacer to align the hinge with the top of the rails.

Then pre-drilled the holes.

Hinges will permit some adjustment.

I made a second spacer to place the hinge on the case one hinge with taller.

Case spacer to ensure the doors are one hinge width above the bottom of the case.

Then I installed the hings on the doors first then the case.

Hinges installed.

Bi-fold door 1/2 open.

Bi-fold doors all the way open with support bar still in place.

I used Marc Spagnuolo plywood wall cabinet no mortise hinge installation video as a guide for what I ended up doing.  I tried to photograph most of the steps.  

I was able to use the hinges to create even space around all door edges.

Then I cut two different spacers.  One spacer placed the hinges at the same location on the doors (in line with the rails).  Then I cut a second spacer that was a hinge space taller to place the hinge on the case side.  This ensured that the door doesn’t drag on the case bottom and left a hinge width space.

As usual, you can right click on the pictures to see them in larger size.