Tips for using PCD: https://github.com/kvannotten/pcd
... I also wanted [range downloads], but then I first used the seq and parallel programs. It's a very unix-y solution, but it turns out ids being integers is great. You may need to install and play with seq and parallel a bit, but this works for me:
episode downloads (echo must be removed for real downloading):
$ seq 4 10 |parallel echo pcd download mypodcast {}
pcd download mypodcast 4
pcd download mypodcast 5
pcd download mypodcast 6
pcd download mypodcast 7
pcd download mypodcast 8
pcd download mypodcast 9
pcd download mypodcast 10
Combined with cron and a Mac automator action that displays a notification when files in my podcast dir change, I feel like I have a complete system that works for me.
cron example to download from podcasts 1-7 in the evenings
# podcasts
10 18-23 * * * cd /Users/john/Podcasts && /Users/john/go/bin/pcd sync >/dev/null 2>&1 && pcd sync && seq 7 | parallel /Users/john/go/bin/pcd download {} >/dev/null 2>&1