Take an old client where reading data using cps.dll is supported, analyze how the resources are read, see how cps.dll is initialized. Initialize cps.dll, redirect resource reading to the symbol uncompress from cps.dll, restore the mention of cps.dll and uncompress in the client's hex code. That's it, now you can patch this exe through the GRF editor by creating your own cps.dll.
You can start small - open the exe with any hex editor, write and save:
63 70 73 2E 64 6C 6C // cps.dll
Now try using the GRF Editor on the updated exe and create cps.dll.
You did it! But apparently, that won't be enough for now... but you know, I'm always ready to help!