How about enabling custom tagging, using substitution parameters?

The particular use case I have right now is that my router's DLNA server sorts programmes by their title tag, and I therefore need a title tag like this: <00episodenum>._<episodeshort>
At the moment I use --tag-longepisode, but this means it sorts like this:

1. Blah
10. Thing
11. Other thing
2. Etc

I was surprised this didn't seem to be supported already. Or perhaps it is, and I have stupidly missed it ... ?