PhoenixFD 3.0 is here. I'm enjoying it very much and I've created a tool to help in the process. PhoenixFD already offers a checkbox option to generate smoke and fire previews during simulation if you're in GPU mode but that option is not offered with the liquid simulator since it does not use the GPU. Here is a script that will automatically capture viewport previews (GPU or not) to the directory your 3DS Max file is saved (in nicely organized folders, of course). Here's how to use it (jump to the bottom to go directly to the download link).
The script was built to work with versioning of your 3DSMax files so if you use a number at the end of your file ("001," "01," etc.) it will also contain the appropriate version number in the EXR filenames. However, it is not necessary to use a number. It's up to you.
First activate the "Use Script" option in the PhoenixFD container.
Then just select the "Edit" button, clear all contents and replace with the provided script. That's it! Previews will now be generated in the same directory your file is saved, in folders named after the file name. If you iterate your file from "001" to "002," the script will automatically create a new directory for the new file name when you begin the simulation. This way, you can keep previews organized and easily keep track of which preview goes with each file.
Please feel free to  use at your own risk. Always back up your files before using scripts you download from shady websites like this.