Force Feedback can be difficult, especially since they work in wildly different ways depending on the game.
Simple Type:
The simplest and best setup are those that do all of the calculations in software and simply output a force and direction.
so you can imagine 1 bit that specifies clock wise or counter clockwise and then say 4 or 8 bits that produce a number representing the "strength" of the pull in that direction. The software obviously gets a positional feedback from the steering wheel pot.
Complex Type:
Some systems, both new and old actually off-load the FFB processing to the motor control board. it will send information like "simulate a rumble effect" or "simulate a hard pull to the left" and they can even have the board layer effects so it can simulate a hard pull and a rumble at the same time.
I know that games using the HAPP FFB Driver board use the Simple Type setup, I picked up the hardware from an Atomiswave Faster Than Speed and the board is really clearly marked. The GameCube also works this way as I found good documentation on the FFB wheel protocol at one point.
Direct X Drivers actually provide a software version of the complex setup where the game can tell the driver which effects it wants and then the driver sorts it out.
Some PC games work both ways though, where if the hardware supports effects the driver will simply pass that information along to the hardware instead of doing it in software. A number of Raw Thrills games (like Need for Speed and Fast and the Furious) do this. they use a motor control setup made by a 3rd party VR company known as the "immersion" board. that actually had 2 separate boards that work together. One is the complex type effects board and the other is the simple type motor control board. Newer revisions of this combine the two together into a single board.
If you look up Howard Casto on BYOAC he's done a lot of work with monitoring bits in memory to extract FFB data and other information. He's been working on a custom build of the PC version of Outrun 2006 to enable a bunch of features that were removed from the arcade version when ported to PC. it's pretty interesting stuff.
So the first step would be to determine how most Model 3 racers output their FFB data, if it's workable you could then build a tool to monitor those bits in memory and then you've got to figure out how to hook them into the output that the Ringedge hardware expects.
