I've written a new compressor and decompressor for the big data segments in DKC2 and DKC3. I've packaged it as a library, but I've also included standalone command line utilities too.
These might not be too useful on their own, but it might make it a bit easier to do other things. The general process for editing would be:
1) Decompress tileset/tilemap/metatiles
2) Convert the raw data to a format that can be edited
3) Edit data
4) Convert the edited data back to the original format
5) Compress the data and hope it fits
Source is included and license is MIT if anyone is bothered about that sort of thing. If anyone wanted to use it to build an editor or some other tool or utility, then great.
There were a more few things I wanted to try in an attempt to improve the compression ratio, but I'm a but worn out from working on it and suddenly a bit busy too. If I hold off releasing it it might end up never getting released, so here it is.
(bd_comp is deprecated, please use dkcomp for better compression ratios!)