Best way to delete old Radio posts wholesale?

I’ve been using Radio to run my Mediajunkie page after migrating this weblog to Movable Type, and I recently added Adsense ads from Google to the pages. I’d like to republish the whole site to get the ads on to the archive pages, but the problems is that the first 1000 or so posts are really from Radio Free Blogistan and don’t need to be republished at Mediajunkie.com.
These old posts still exist at their old archived locations, both at blogs.salon.com/0001111 for posts from before October 2002 and all of them were republished at radiofreeblogistan.com using the Radio day-archive format. All the posts up to the migration are also republished using the Movable Type individual-entry archive format. So there’s really no need for a third set of all those posts to confuse Google with.
My question is, what is the best way to bulk-delete all the posts at Mediajunkie older than the migration? I don’t want to navigate to each date in my desktop weblog homepage and manually delete all the entries. That can’t be the best way. Do I delete the local versions of hte files (maybe even the folders) and then wait for Radio to upstream away the hosted versions, or do I go into the .root file that contains all the posts and delete them there.
I’m quite sure that if I do it the wrong way I risk corrupting data and leaving unhealthy loose threads hanging. Has anyone dealt with this situation? Any recommendations? I’ll probably wander over the the Radio discussion boards at UserLand to post this question too, but I know the UserLand guys must be pretty busy with other things, so I’d really just be asking the userbase for help, as I’m donig here.