The reply at that link by Charles Nurse is not correct. Legacy packages are not installed correctly at all. If the "legacy" package is packaged up in the standard method, the package is installed entirely in the skins directory. For example, lets call the skin "ABC". Normally, container files are zipped up into "Containers.zip" and skins are zipped up into "Skins.zip". Those two zip files would be zipped into "ABC.zip" and installed as the skin file, and this would automatically install the skins from skins.zip into the skin directory called ABC and the containers from containers.zip would be installed into the containers directory ABC (_default/skins/abc and _default/containers/abc respectively). In DNN 5, installing the ABC.zip as the skin package actually takes the two zip files and creates directories in the skins directory with those names and then places their files into those directories, so you end up with _default/skins/abc/skins and _default/skins/abc/containers. DNN 5 then finds no files in the _default/skins/abc directory, so not even the skin is usable. Basically, users are going to be confused by all this conflicting information about legacy installs supposedly being supported when they are not 100% supported unless these packaged skins and containers are unzipped and the skins and containers zip files are installed separately. In my opinion, this doesn't make things easier for the end user who could install a skin/container package in one step previously and now have to go through two separate installs with multiple pages of clicking next, next, next, etc. This really creates a lot more work and a lot more steps for the end user instead of streamlining or improving anything. This really needs work to move it forward instead of the current state of moving backwards and complicating the whole process with extra steps for the end user.
With all that in mind, I was able to install legacy skins and containers when the skins and containers zip files are installed individually and not inside any type of main zip file that contains both. I was also able to create skin packages for DNN 5 and was able to install those successfully, but again the skins and containers must be installed separately or it won't install successfully. It would have been nice to have this documented.
By the way, the "documentation" that is available in the downloads page and labeled as DNN 5 documentation is still the same outdated skinning documentation from 3 or 4 years and a hundred or so upgrades ago. If it's not the actuall DNN 5 documentation and there isn't any available at this point, then that should really be removed from the downloads page and marked as "coming soon" or something more appropriate.
Are there plans to add the combined skin/container package installation into DNN 5, or are the simpler installs just as gone as the simpler days of our youth? It's not the worst thing that could ever happen to have to package things separately and explain to clients that they can no longer install skin/container packages in one easy step. But, this is a fast food society where we all want someone to "make it easy for me" and throwing this new, more time consuming install process is not going to make anyone happy at. We'll just all begrudgingly make use of it the best we can...