I would like to try creating a custom driver for a trackpad of mine. Could you please recommend an opensource driver to start with? My search turned out nothing, so I hope there actually any skeleton code to begin building from.
Is it a USB HID device? If so, it should be pretty easy to read data from the device.
Check out this code (C#) for example.
There is also the UMDF (User Mode Driver Framework) that supposedly allows writing drivers for USB-like devices in user mode. I have never used it though. There are a couple of sample drivers to download.