Thanks to suggestions from Steve and Will, I decided to stop trying to figure out the elegant solution to getting podcasts on my Treo and go at it much more simply. (For the record: the elegant way would be having the MP3s sync to the Treo during a Palm HotSync.)
Since the Treo’s built-in memory is limited, the MP3s have to be stored on an SD card, and I already own a 1 gigabyte SD card for the Treo. Both Steve and Will recommended an SD card reader, which would make the copying/syncing of files to the card much simpler (not to mention a whole lote faster) — and yesterday, Fry’s had a 12-in-1 card reader for just $4.99 (ordinarily it’s $14.99).
Bingo. Now I can have my podcasts auto-downloaded to the SD card (which is mapped as a drive in Windows), then just drop the card in the Treo and play the MP3s. (Of course, that means I have to remember to remove the card!)
Bottom line, this is a simple, easy way to ensure that I can regularly get new podcasts to listen to on my Treo.