Is it possible to set a block to give a negative value, and thus, put out a negative temperature? If not, could this be implemented for configs in a future update?

How do you add different items to your config file?

Negative values should indeed already be supported.

I support this, Ice would normally lower our temperature down, packed ice even more perhaps, but at the same time, it would defeat the machines purpose of the mod.

There is a config file for block temperature. I've added many items to mine. Even added lit torch to add a little heat. It appears to work for me.

Wish there was a biome adjustment. I would like to over ride it. but have not looked at forge to see if they allow it. Since this mod realize on forges default value for the biome default temps.