[kernel] How do I configure modprobe to find my module?

You can make a symbolic link of your module to the standard path, so depmod will see it and you'll be able load it as any other module.

sudo ln -s /path/to/module.ko /lib/modules/`uname -r`
sudo depmod -a
sudo modprobe module

If you add the module name to /etc/modules it will be loaded any time you boot.

Anyway I think that the proper configuration is to copy the module to the standard paths.