Thanks for the link. I didn't realize anyone tried to do that before SuperSpawn. Well, there was a spawn editor out there at one point but it only worked with CM 1.30 and the creator took down all her stuff.
Anyway, just use SuperSpawn that comes with EE. It's the same idea, just increasing mob density. The difference is my mods are guaranteed to be compatible. That thread is from 2009, so is built on an ancient version of the game. Would cause all kinds of issues.