If you want to parse Microsoft Cabinet files in Python you probably should just install gcab, and use the GObjectIntrospection bindings for that. GCab is a much better library than this and handles many more kinds of archive.
If GCab is not available to you (e.g. you're trying to run in an OpenShift instance on RHEL 6.2), this project might be somewhat useful.
Contributors welcome, either adding new functionality or fixing bugs.
See also: https://msdn.microsoft.com/en-us/library/bb417343.aspx