Don't think so. You can create a new filesystem with uml_moo, which is then identical with the cow-file. You can mount that. But of course it is no cow-file any more after that but a regular filesystem-image. You can't change it back to a cow-file.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hello!
Is it possible to mount partitions of cow-images loopback on a linux-system (read/write)? and how hard would it be to add the ability to do so?
Thanks in advance, lg Clemens Eisserer
Don't think so. You can create a new filesystem with uml_moo, which is then identical with the cow-file. You can mount that. But of course it is no cow-file any more after that but a regular filesystem-image. You can't change it back to a cow-file.