Unsure, it does come with the game, and usually these things need the game installed to run, but I don't know if it's available seperately.
You could use any matrix editor, then convert your level data into a heightmap image. I'm in a similar predicament myself, hate using PSP to create heightmaps, but don't really want to spend weeks and weeks on my level editor. The annoying thing is the byte limit, really, when you look at the resolution on a 256 greyscale heightmap, it's really poor - I think DBPro actually does it's own tweaking to avoid the blocky resolution, which means you don't really have exact WYSIWYG no matter how you edit your levels. This is all a major drag when your trying to plant buildings etc that like nice flat foundations.
Van-B
Muhahahahaha.