Well actually you can share them. It's not perfectly integrated and takes some effort but it'd work.
You copy all the sound files you use (per Scenario) into one folder on your computer (Preferably in a path everyone could use, something like "C:\Softrope\Scenarios\Jungle\"). Then you save your Scenario file inside that folder, too. Open the scenario file with a text editor (notepad++, or if nothing else works even ye olde windows notepad) and change all paths to all those files to their new home, the just created folder, leave all other settings in them alone. Save the file again and try it out inside Softrope, it should work just as before, only that it now uses the files inside that folder. Add a text file in the scenario folder that says where it's supposed to be, pathwise, so that we're able to put it in place accordingly later. Now zip that folder up ito a nice package and upload it to a file hosting service like Rapid Share or Mega Upload and present us the download link here.
You can do that with either each scenario at a time or just zip em all together at once (but that'd prolly result in a very big file, that might exceed the max capacity of the hosting service).
Sure there is an issue with sound files that are protected by copyright, but as this is a very small community, it's more like lending a CD to a friend than "mass distributing" it so I guess it's not THAT much of an issue.
To make sure only "we" can use the file you could always password protect the zip or rar archives and post the password here in the forums.
Cheers ;)
The Dukey