I was able to do it (somewhat) in Windows like so:

I made a .m3u playlist in one of my shared folders containing this:

#EXTM3U

dshow://

Then I added m3u as an extension within the Filter Extensions plugin, so it would show up in the shared folder. http://localhost/vlc-shares/public/config/index/key/filterExt

This let’s me watch whatever the default for DirectShow is set to within VLC. Unfortunately, you cannot do anything more than just “dshow://”. For instance, you cannot make separate playlists for individual TV channels or webcams. As far as I know, this is a bug within VLC itself. It doesn’t matter if you use .xspf playlists, either. When opening a playlist in VLC containing DirectShow devices, you are limited to whatever the default DirectShow device happens to be.

To change the default DirectShow device, in VLC:

Tools > Preferences
Set “Show Settings” (bottom left) to All
Input/Codecs > Access Modules > DirectShow

From there, you set what the default video and audio devices are and configure them accordingly. [Note: For my TV tuner cards, I only have to select one as the video device and I just leave the audio device at “default”.]

NOTE: You may need to disable auto thumbnail creation when trying this out. I did, just in case.