Most good shoulder(PA) mics will have a sound passthough meant for those clear ear tubes. Just get a 3.5mm to 3.5mm jack (if that is the size used) and use that to pump sound into the sordins and use the PA mic to talk.
Like so:
Here is one that should work, kinda pricey, but so were the sordins.
http://www.911supply.ca/collections/...-3-5mm-kenwood
Im sure there are other options out there though.
You could also just get you hands on a raw kenwood connector or lapel mic/ear phne combo and put your own 3.5mm jack on it. (cut off the earbud)
The AUX connector on the sordins is supposed to work with media players so you should not have any impedance issues.
The incompatibility usually found with sordins has to do with the mics and not the speakers. All that had to be done with mine when I got it set up for civ comms was replace the mic, a $7.50 part.