For more info (plus the download link), see the VOGONS thread - all sorts of cool stuff in there, like videos recorded from real hardware, and a DOSBox build patched with some useful additions for running this. However, I've had a request or two for the technical nitty-gritty, so here's where I'm gonna dump it (careful what you wish for? ;-))
This patch started out as direct modification of the .EXE, following some disassembly and analysis. I "ported" it to the CKPATCH format (for in-memory patching) only when I was done, by generating a binary diff. This is why my notes will follow the disassembly, which is easier to comment on; all offsets are relative to the beginning of the load image (=file offset minus 2C00h) in v1.4-Apogee of the CGA executable.
For new data, I found some 119 bytes that could be reused at offset 31548h. In KEEN4C.EXE this has the color tables for the EGA fade routines - they're still present in the CGA executable for no discernible reason. I ended up using only 36 bytes here, for extending the color tables used by various CGA drawing routines.