Here's where it gets really "hacky." For the camera mount, it's important to have fine adjustments so you can get as much of the film image in your camera's field of view as possible. This increases the final resolution of the movie file. In other words, the closer you get the more pixels you will capture. But when you're that close you need to make very small adjustments to your camera's position. The cheapest way I could find to have fine controls was to disassemble a microscope for the vertical positioning, and use a macro photography plate for the horizontal positioning.
Why a microscope? It has fine-tuning knobs for positioning, is made with parts that are guaranteed to be exactly vertical and horizontal, and it was cheaper than buying separate parts and making one myself.
If you go the microscope route, you will need to build a mounting plate to affix the post to the slider bearing that fits on the t-slot rail. I've posted some pictures of my solution here, which was made of two acrylic plates glued together, then mounted to the sliding bearing. Your solution may have to be different, but the following general steps are what need to happen.
2. Mount the microscope post to the slider bearing. You will have to fabricate your own and its design will depend on the microscope you got.
3. Mount a standard camera plate to the macro-adjustable camera plate.
4. Mount the two plates to the microscope's horizontal platform.
5. Slide the camera mount assembly onto the 2" t-slot rail and tighten the bearing's brake arm to hold it in place.