auto prune when reaches 1000

[Trasion]

I have a forum section with an automatic feed, and a lot of stuff piles up there. I don't want to waste bandwidth on having way too many threads. So right now I have two sections that get feeds, and I want it so that each section can only have up to 1,000 threads in it. The oldest (post date wise) is deleted, so there's always only 1,000 threads.

How can I do this? Or do I need to do it manually with the pruner each time?