3dsMax 2018.4 has been released today.
One of the feature is the full BiFrost channel support for PRT export.
You can export all BiFrost channels even with custom channel names.
As of now, export channel setup is only exposed to Maxscript.
So, I made a UI for that.
You can turn on/off channels and rename channels.
Installation is simple.
Download the zip file and drag and drop to your viewport.
You can find the script in csTools > MaxFluidsPRTExportChannelSetup.
It is a macroscript so you can make button, menu or shortcut.
It will also show up in Global Search(X)
As always, it is free!