[DARKPLACES] If I make something new with QuakeC, how do I place it in a level? Thread

I've been looking into DarkPlaces modding since 3DRealms announced their new FPS, based on the DarkPlaces engine. So far I've experimented with purely architectural level design (for reference, I use GTKRadiant 1.5). You can see some screenshots of what I've done here: Imgur.com

Now I would like to try writing some QuakeC code, but something is stopping me. If I make something new (e.g. a new weapon or a new enemy), how do I add it into a level from the level editor? I've downloaded a couple of new weapons made in QuakeC, and I can only add them to my own inventory at runtime, via "impulse" commands!