Hi,
The adau1761-3.10 branch should work fine on 3.10. Just merge it into your checkout of the boundary devices tree.
E.g. go to your git checkout and run:
git remote add adi_github https://github.com/analogdevicesinc/linux.git
git fetch adi_github
git merge adau1761-3.10
As for the other question there can be many different reasons why the sound card does not get registered. You can check the files in /sys/kerne/debug/asoc/ and see which components have been registered and compare this to the components you'd expect to be registered. This will give you an indication why things don't work.
Also be aware that the module itself only registers a driver, you'll still need to register a device that binds to the driver. Only when both driver and device are registered the code will be executed. If you are not familiar with the Linux device driver model have a look at https://www.kernel.org/doc/Documentation/driver-model/.
- Lars