Good morning mhahn,
Thanks for getting in touch, Ross from Two notes here. There are a few options available to you!
Assuming you are using 2 mono files, you could bounce these down as a Stereo file and run them through the WoS plugin on a Stereo track. Alternatively, if your DAW permits, you can route the two hard-panned Mono channels to a Stereo Bus and apply the Wall of Sound Plugin to this Bus. Finally - and a little more CPU intensive - you can add the Wall of Sound Plugin to each of your Mono channels and ensure all microphone configurations inside the software are hard panned according to your needs.
Please let me know if this helps and if there is anything else I can help you with, please do not hesitate to let me know!