I don't think so also you can't add textures you have to replace them, it doesn't work like in source games that you can add textures,models and use them.

As far as I know you can't seeing as all the files have to be in the bundles for audio. And even if you were to be able to add files to bundles, It may be quite difficult. Well to be honest I haven't really messed around with Audio at all, so I could be wrong in the possibility of doing it.

thanks for the replies :D