Streaming MOH FROM a registered extension (PAP2T)

I enabled SAS (Streaming Audio Service) on a Linksys PAP2T and connected the audio source to the FXS port via a 3.5mm to RJ11 adapter.

This ATA is registered as extension 100 and now, anytime I dial x100, I hear the audio source (works great).

Now I would like to see if there is a way to have asterisk use extension 100 as the MOH source. We have a specific application for this layout where we use ATAs in various locations to capture real-time audio and need to be able to set it as MoH for different groups to dial in and hear.

Another option would be if there was a way to auto add this extension to an existing meetme conference anytime a user dialed into that conference (that may be a tougher approach).