Hey, I'm kinda new to modding and editing and stuff, so I was wondering, is there a program I can use to create a map where I can choose what biomes to be where? I was thinking of making this HUGE map for a RP server, having a HUGE desert in the middle, and different kingdoms at the edges. Is this possible?
The algorithm doesn't need to be changed I don't think. That part functions to determine what biome new chunks should be marked as. This info is presumably stored somewhere, I guess the OP is asking for a tool to be able to say "these chunks are X" and change the value for those chunks to X.
In theory it shouldn't be that hard. That's if that's how biome info is stored.
That info is not stored somewhere. Biome isn't even defined per-chunk, it's per-x-z-coordinate.
That's impossible*, if you expect to also have control over terrain colors and the type of weather you experience.
* Conceivably someone could produce a mod that changes the existing biome system to save and load generated biome data from disk, rather than compute it on the fly. And then you could develop a new editor that can recognize and manipulate this data. This change would probably be as jarring as using MCR before MCR became a part of Minecraft.