Well, I solved this problem another way. The key to its solution is noticing that the Sansa player has two USB modes: MSC and MTP.
MSC, the default mode in the player, does not allow proper transfer of the id3 files.
OTOH, MTP, the Microsoft Media Transfer Protocol, does allow proper transfer of these files.
We now have the little issue of enabling MTP on the desktop and the player.
In my case, this surmounted to:
- Update Windows Media Player to version 11.
- Install the Windows MTP porting kit.
- Switch the player to MTP mode in the settings.
- Connect the player to a USB port.
- Allow Windows to auto-detect and install an MTP-based driver for this player.
- Edit the id3 records using the Windows Media Player.
- Copy the mp3 song files to the player using the MTP device.
It works. I hope someone finds the documentation useful.